A new study has found something remarkable: the activation of a particular type of immune cell in the brain can, on its own, lead to obesity in mice. This striking result provides the strongest demonstration yet that brain inflammation may be a cause, rather than a consequence, of obesity. It also provides promising leads for new anti-obesity therapies.

The evidence linking brain inflammation to obesity has been building for some time. Consistent overeating causes stress and damage to cells in the body and brain. This damage results in a response from the immune system that has a wide range of effects.

Some of these effects help to reduce the problems caused by overeating, but others seem to make things worse. For example, in the hypothalamus – the part of the brain that controls, among other things, eating and activity – inflammation causes problems such as leptin resistance that interfere with the regulation of body weight.

Leptin is a hormone that is released by fat cells and provides the brain with information about the amount of energy stored as body fat. Normally, neurons in the hypothalamus that are sensitive to leptin will use this information to regulate eating and activity as needed to maintain body fat within some desired range.

In obesity, however, these neurons become insensitive to leptin. As a result, they no longer trigger the decrease in hunger and increase in energy expenditure that are necessary to lose excess weight. This is why the vast majority of attempts by obese people to lose weight fail– inflammation causes the brain to fight against it every step of the way.

So brain inflammation clearly plays an important role in sustaining obesity. But could it also be one of the primary causes of obesity in the first place? The onset of brain inflammation coincides with the other changes that take place in the body and brain as a result of overeating and weight gain. But whether brain inflammation actually causes the development of obesity is not yet clear. The results of the new study, however, demonstrate that the activation of a particular type of brain immune cell, microglia, initiates a cascade of events that do indeed lead directly to obesity.

Manipulating microglia in mice

In the study, researchers at the University of California, San Francisco and the University of Washington performed experiments on mice. They found that altering the activity of microglia in the hypothalamus allowed them to control the body weight of the mice independent of diet.

The researchers began by testing the effects of reducing either the number of microglia or their level of activity. They found that both manipulations cut the weight gain that resulted from putting the mice on high-fat diet in half.

They then tested the effects of increasing the activity of microglia. They found that this manipulation caused obesity even in mice that were on a normal diet. This latter result is particularly surprising. The fact that obesity can be induced through microglia – rather than directly through neurons themselves – is an indication of how strongly the brain’s supporting cells can exert control over its primary functions.

So artificial brain inflammation can cause obesity in mice. Of course, that doesn’t mean that natural, diet-induced brain inflammation does cause obesity in humans. But these new results suggest that this idea is worth taking seriously, particularly given that fact that potential solutions to the obesity crisis are in short supply.

This new study alone has already identified several possible targets for anti-obesity drugs. Intriguingly, one of the same drugs that was used in the study to decrease activity in microglia is also being tested in human cancer trials, so initial indications of its effects on body weight should be available soon. But either way, a deeper understanding of the role of brain inflammation will help to clarify the causes of obesity. And hopefully prompt ideas about how it can be avoided in the first place. 

SEE ALSO: Regular alcohol drinkers have lower risk of diabetes, according to a huge new study

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NOW WATCH: Doctors have finally found a more accurate way than BMI to determine whether your weight is healthy

The thought of a cupcake, skillfully frosted with fluffy vanilla icing, may put a smile on your face, but research suggests that, in the long term, a sweet tooth may turn that smile into a frown – but not for the reasons you think.

In a new study, published in Scientific Reports, my colleagues and I found a link between a diet high in sugar and common mental disorders.

The World Health Organization recommends that people reduce their daily intake of added sugars (that is, all sugar, excluding the sugar that is naturally found in fruit, vegetables and milk) to less than 5 percent of their total energy intake.

However, people in the UK consume double – in the US, triple – that amount of sugar. Three-quarters of these added sugars come from sweet food and beverages, such as cakes and soft drinks. The rest come from other processed foods, such as ketchup.

At the same time, one in six people worldwide suffers from a common mental disorder, such as a mood or anxiety disorder. Could there be a link between high sugar consumption and common mental disorders?

Earlier research, published in 2002, examined the link between depression and sugar consumption in six countries. The researchers, from Baylor College in the US, found that higher rates of refined sugar consumption were associated with higher rates of depression.

Since then, a handful of studies have investigated the link between added sugar consumption and subsequent depression.

In 2011, researchers in Spain found that when they grouped participants based on their commercial baked food consumption, those who ate the most baked food had a 38 percent increased chance of developing depression compared with those in the group with the lowest intake.

The association remained even after accounting for health consciousness and employment status.

In 2014, researchers studied the association between sweetened beverages in a large US group. They found that sugar-sweetened and artificially sweetened drinks (diet drinks) could increase a person's risk of developing depression.

And, more recently, a 2015 study, including nearly 70,000 women, found higher chances of depression in those with a high added sugar intake, but not in those with a high intake of naturally occurring sugars, such as those found in fruit.

Trying to explain the link

We are still not sure what causes depression, but some researchers believe that biological changes are at the root of it. Some of these changes could be influenced by sugar and sweet taste.

For example, a study in rats found that diets high in sugar and fat can reduce a protein called BDNF that influences the growth and development of nerve cells in the brain. This protein is thought to be involved in the development of depression and anxiety.

Another possible biological cause is inflammation. High sugar diets can increase inflammation – a protective reaction of the body, normally directed against microorganisms or foreign substances.

While common signs of inflammation, such as redness, are far from a mood disorder, the symptoms that keep us in bed with a cold are much closer, such as low energy and being unable to concentrate.

Ongoing research suggests that mood disorders could be linked with inflammation, at least in some cases.

Dopamine is another possible culprit. A study using rats earned headlines for suggesting sweet foods could be as addictive as cocaine.

This might be due to affects on dopamine, a brain chemical involved in the reward system. Dopamine is also thought to influence mood. And addiction is itself associated with a higher risk of developing a mood disorder.

Finally, sugar intake could be associated with other factors, such as obesity, which itself is related to mood.

But these associations could also reflect a reverse phenomenon: low mood could make people change their diet. Sweet foods could be used to soothe bad feelings by providing a short-term mood boost. And low mood and anxiety could make simple tasks, such as grocery shopping or cooking, so difficult and exhausting for the sufferer that they might start to avoid them. Instead, they might opt for junk food, takeaways and ready meals – all of which have a high sugar content.

What our study adds to the debate

For our latest study, my colleagues and I put the reverse association idea to the test. We used sugar intake from sweet food and drinks to predict new and recurrent mood disorders in a group of British civil servants. We also investigated whether having a mood disorder would make people more inclined to choose sweet foods and drinks.

We found that men without a mood disorder who consumed over 67g of sugar had a 23% increased risk of suffering from a mood disorder five years later, compared with those who ate less than 40g. This effect was independent of the men’s socioeconomic status, physical activity, drinking, smoking, other eating habits, body fatness and physical health.

We also found that men and women with a mood disorder and a high intake of sugar from sweet food and drinks were at higher risk of becoming depressed again five years later, compared with those who consumed less sugar. But this association was partly explained by their overall diet.

We found no evidence for a potential reverse effect: participants did not change their sugar intake after suffering from mood disorders.

Despite our findings, a number of questions remain about whether sugar makes us sad, whether it affects men more than women, and whether it is sweetness, rather than sugar itself, that explains the observed associations. What is certain, though, is that sugar is associated with a number of health problems, including tooth decay, type 2 diabetes and obesity. So cutting down on sugar is probably a good idea, regardless of whether it causes mood disorders or not.

SEE ALSO: The shocking amount of sugar in 9 'healthy' foods

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NOW WATCH: Scientists say combining these 2 activities could be an effective way to fight depression

Breast cancer is the most common cancer among women around the world.

There are a number of habits that put us at greater risk of breast cancer. Knowing what those habits are can help you take steps to decrease the risk. 

The American Institute for Cancer Research detailed the factors that can put women at greater risk for breast cancer. While there are some things women can't control, certain lifestyle choices can have a big impact on a woman's risk. 

Here's what you can do to decrease your risk. 

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Exercise.

Exercising regularly and vigorously is one way to decrease your breast cancer risk. Studies have found that the risk of developing breast cancer is lower for women who are active than those who are inactive. 

It's something researchers are still studying. In 2016, Fitbit teamed up with leading cancer institute Dana Farber Cancer Institute to launch a 3,200-person study that looks at how breast cancer recurrence, or instances in which the cancer returns after a first round of treatment appears to knock it out, is affected by weight loss in overweight and obese people.

Maintain a healthy weight.

Obesity has been linked with an increased risk of breast cancer, along with pancreatic, esophageal, colorectal, and thyroid cancer, according to the National Cancer Institute. Maintaining a healthy weight through diet and exercise can be a way to keep your risk of breast cancer low. 

Breastfeed.

Breastfeeding has been linked to a lower risk of breast cancer for mothers. In 2002, a massive study of nearly 150,000 women found that for those who breastfed, the longer they breastfed the more protected they were against breast cancer.

For every 12 months a mother breastfed, her risk of breast cancer went down by about 4%. The World Health Organization recommends that mothers breastfeed for their babies' first six months. 

"Eat fat, get fat" has been the conventional wisdom guiding American diets for the past two decades.

Yet more and more research suggests this kind of thinking is dangerously misguided.

Instead of finding evidence that low-fat eating plans offer health benefits, dozens of studies have suggested instead that these kinds of diets are unhelpful or potentially harmful. And new research points to another food category that could be the real problem: simple carbohydrates.

A large new analysis published August 29 in the journal The Lancet compared more than 135,000 people on low-fat and low-carb diets across 18 countries. The researchers found that low-fat diets were more likely to be linked with death from all causes, and found a higher likelihood of heart attacks and heart disease as well. People on low-carb diets, on the other hand, had significantly lower risk of both of these outcomes.

"Global dietary guidelines should be reconsidered in light of these findings,"the researchers wrote in the paper.

Why low-fat diets don't make people thin

Several other recent studies of people on low-fat eating plans have shown similar results. An eight-year trial involving almost 50,000 women put roughly half of them on a low-fat diet, and found that the women on that plan didn't lower their risk of breast cancer, colorectal cancer, or heart disease. Plus, they didn't lose much weight, if any.

The body needs some fat to function, so people on diets that lack this ingredient won't feel full longer term.  Plus, fat helps you absorb vitamins and minerals, and is essential for blood clotting and muscle movement. It's also needed to build cell membranes (the shells that house each of your cells) and the protective shields around your nerves. 

Part of the problem with low-fat diets is the processed, "low-fat" foods that are often advertised as healthy. When food-makers remove the fat from a product, they also remove most of its flavor, so often wind up adding other "filler" ingredients like sugar to compensate.

Because foods high in simple carbohydrates like white flour and sugar lack protein and fiber, they only satiate you briefly, leaving you hangry later. This is why they're often called "empty calories."

Not all fats are created equal

Some fats are healthier than others, as a recent study published in the Journal of the American Medical Association revealed.

For that study, researchers tested what happened when thousands of people swapped out 5% of their calories from saturated fat (the type most often found in meat and dairy products) with calories from mono- and polyunsaturated fats (the kind found in olive oil, fish and nuts). They found that doing so was linked with numerous benefits, including a reduction in the risk of death and conditions like heart disease and several neurodegenerative diseases.

"Not all fats are created equal," Harvard nutrition professor Dr. Frank B. Hu, a lead author on the study, told The New York Times. "We should eat more good ones from fish and avocados, instead of animal fats," he said.

According to a health blog maintained by the Harvard Medical School, healthy fats include those from nuts, fish, and avocados; unhealthy ones are trans fats found in processed foods, and saturated fats "fall somewhere in between."

Overall, the take-home message is simple: fats from vegetables, nuts, plants, and fish are a healthy component of any diet, while an excess of simple carbohydrates is probably not.

SEE ALSO: Americans have been making a huge diet mistake for 100 years — here's what they should do instead

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NOW WATCH: Here's what happens to your body when you stop eating carbs

The INSIDER Summary: 

• A mom wrote an op-ed on why she chose not to send her child to a school with "extremely overweight" teachers. 
• The mom discusses body-positivity, fat-positivity, and fat-shaming as well as how she felt vilified for her opinion. 
• The woman was not only worried that the teachers wouldn't physically be able to keep up with the kids, but that their body-types would send a message about obesity to her child.
• There are mixed opinions on the subject.

Experts seem to agree that weight doesn't necessarily provide a complete picture of your health or fitness level. UK mom Hilary Freeman disagrees, however, and says a teacher's weight impacted her decision about where to send her daughter to school.

In a controversial essay for The Daily Mail, Freeman explained why she decided not to send her child to a nursery school that employed people she called "extremely overweight."

Freeman writes that she felt a "sense of unease" watching the nursery assistant play with her 2-year-old daughter. She expressed her concern for whether or not the assistant would be able to act with "lightening reflexes" that she deemed necessary when watching over a child.  

"She was only in her 20s, but she was already obese — morbidly so," Freeman wrote. "She moved slowly and breathlessly, her face flushed."

The physical fitness level of the nursery employees wasn't Freeman's only concern. She also feared the physical characteristics of the teachers would send an unhealthy message to her daughter.   

"I couldn't help worrying about the message this was sending to the children in their care: that being very fat is normal and — when children adopt role models so readily — even desirable," she wrote. "My anxiety about this was the main reason I chose not to send my daughter to that nursery." 

Freeman did not initially want to tell people why she chose to send her child to another school due to her fear of being shamed for her opinion. 

Originally, Freeman lied to other parents as to why she chose one school for her child over the other. Instead of telling fellow parents the truth, she claimed the other school was friendlier to avoid being accused of fat-shaming.

For the majority of the piece, Freeman continued to back up her opinion on "fat-positivity" which she thinks, "has gone too far."

"Originally a response to discrimination against those who aren’t slim enough to fit into society’s beauty ideal, [fat-positivity is] now an excuse for the severely obese to celebrate their bodies," she wrote. 

She detailed her experience with an online Facebook group where she disagreed with a self-proclaimed overweight parent who plans to raise their child to be a "fat-positive" person. Freeman went on to say that people shouldn't be fat-shamed, but that "it was not inevitable the woman's daughter would become fat." 

Freeman also shared her own experience with gaining and losing weight, as well as the ways obesity is related to some health issues. She specifically compared smoking to obesity. 

The essay has raised some controversy and sparked discussions about the body-positivity movement.

The essay has been picked up by numerous media outlets, and the response in the comments section of the original piece is heated. 

"Teaching your children not to judge anyone on face value would be a far better attribute," one commenter wrote.

"Surely she should be looking at whether the teacher was an outstanding teacher or failing teacher rather than the size of their clothes. AND educate your OWN child regarding food and exercise. Instead of teaching your child prejudice that will [not] help society won't it," someone else said.  

A few commenters agreed with Freeman, "I agree with the principle but not everyone chooses to be overweight. Teach your child to make good life style choices rather than to exclude people who don't 'fit' yours. The teacher could have taught her so many valuable things and nobody is perfect."

Freeman's essay, while controversial, touches on the connections between fat-positivity, body-positivity, and fat-shaming. Fat-shaming should be unacceptable and obesity or health problems should not be justified by the body-positivity movement either. Being healthy is important and should be a priority for everyone, but that doesn't mean that you can't be body-positive or love yourself at the same time. Even doctors, although cautions to jump on the body-positivity train, are being more considerate and inclusive when working with patients who are overweight or obese.  

It might help Freeman and others to remember that physical attributes do not determine how smart someone is, how healthy they are, or how good they are at their job, teaching or otherwise. 

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One in 10 of the world's 7.5 billion inhabitants is obese. At the same time, the number of people who are starving or malnourished is on the rise.

That finding comes from a comprehensive new report from the Food and Agriculture Organization of the United Nations. And it begs the question: How can these two seemingly contradictory outcomes be happening at the same time?

Nutritionists and public health experts say both issues can be traced to our diet.

Globally, more processed, caloric foods are available to more people than at any other point in history. Nowhere is the problem of cheap, unhealthy, omnipresent food more apparent than in the US, which in recent years has seen the largest percentage increase in its obesity rate than any other country, according to a recent study in the New England Journal of Medicine.

"We live in a society where making healthy choices and being at a healthy weight, it’s not defaulted toward that,"Andy Bellatti, a registered dietitian and the cofounder of Dietitians for Professional Integrity, told Business Insider. "Unhealthy foods are cheaper and they're everywhere; if you go to any store, you can buy a candy bar at the checkout but not a piece of fruit."

This chronic lack of healthy food is creating what the New York Times recently called"a new type of malnutrition ... in which a growing number of people are both overweight and undernourished."

It can sound counterintuitive, but the authors of the FAO report say it isn't.

"Particularly in high- and upper-middle income countries, food insecurity and obesity often co-exist — even in the same household. When resources for food become scarce, and people’s means to access nutritious food diminish, they often rely on less-healthy, more energy-dense food choices that can lead to overweight and obesity."

For the thousands of people worldwide struggling with their weight, this can make losing weight and keeping it off nearly impossible. Still, there are solutions, Bellatti said.

The first step to sustainable weight loss is being emotionally ready, he said. "You need to be in a mental state where you want to do it. Anytime you force somebody, if they don’t care and they’re not motivated it’s not going to happen."

Once that component is addressed, Bellatti advised setting up a long-term weight loss plan that allows you to make slow and steady progress toward your goals.

"You've got to give yourself two, three, even four years of consistent behavioral changes," to lose weight and keep it off, Bellatti said. "That is hard work. You’re building new habits. And that takes time."

That means instead of aiming to drop three sizes in a few weeks by doing a trendy cleanse, you should start incorporating small tweaks into your daily routine, such as eating more leafy vegetables, avoiding refined carbohydrates like white bread, and ensuring you're getting enough sleep and drinking enough water.

It's important to keep in mind too that obesity is a complex issue that is influenced by things outside of our control, like genetics. But if you're looking to lose weight via behavioral change, experts recommend focusing on long-term, sustainable new habits.

"I'd say nine times out of 10 the people who change slowly and do manageable goals are the people who three years out still have success," Bellatti said.

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The INSIDER Summary:

• INSIDER has rounded up some of the most pervasive myths and misconceptions about sugar.
• For example, sugar does not cause cavities; acid does.
• There's no such thing as a sugar rush — no, extra candy does not make your kid hyper.

We've seen the alarming documentaries, sat through health class lectures, and watched the obesity numbers steadily grow at an alarming rate. Sugar is the enemy, right?

While eating too much sugar is directly associated with obesity and a host of heart and liver-related problems, there are plenty of myths out there with a host of misinformation that oftentimes makes eating even moderate amounts of sugar sound worse than it is. After all, we do need sugar to live.

"We all need sugar — it's the basic building block of what runs our bodies, and, in fact, it's necessary," Dr. Jennifer Haythe, a cardiologist at Columbia Presbyterian Hospital in New York told INSIDER. "But I'd rather my patients have more fruits and vegetables and lean proteins because of all of the overly processed ingredients surrounding sugary foods."

Keep scrolling to discover the truth behind some of the most common myths about sugar.

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MYTH: Some types of sugar are better for you than others

FACT: All "types" of sugar have the same effect on your body. 

"There’s this idea that there are different types of sugar, but that’s a myth," Dr. Haythe said. "Brown sugar, white sugar, honey... they are all ultimately broken down into the same thing: glucose. All forms of sugar are carbohydrates that can be used as glucose."

MYTH: Sugar makes kids hyperactive

FACT: There's no such thing as a sugar high.

"The idea that sugar makes children hyperactive is one of the funniest myths about sugar out there," Dr. Haythe said.

Various scientific studies over the years have determined that in fact there is zero direct connection between eating sugar and hyperactivity. 

A definitive research paper published byDr. Mark Wolraich, chief of Developmental and Behavioral Pediatrics at Oklahoma University Health Sciences Center, concluded that "sugar does not appear to affect behavior in children."

MYTH: Sugar is as addictive as hard drugs

FACT:  There is no conclusive evidence that sugar is addictive.

"There's no evidence that sugar can act as a gateway drug," Dr. Haythe said. "You can't get high from sugar, and there's no conclusive evidence that sugar is addictive."

There are multiple conflicting studies concerning the subject of sugar addiction. One French study published in 2013 links cravings for sweets with the "reward" center of our brains that are induced by addictive drugs. The study concluded that sugar can be even more addictive than cocaine. 

But other doctors and researchers contest that study's findings, stating that you only see addiction-like behavior in rodents when the animals are restricted to eating sugar for a certain time frame each day. When the test subjects are allowed to eat sugar whenever they want — like humans — the addictive properties vanish. 

Diets are made to be broken.

At least that's what a small new study, which found that breaking up extended periods of dieting with more normal eating, suggests. People in the study who took two weeks at a time off of their diet lost more weight than peers who stuck to it for the same amount of time. They also kept more of the weight off for longer.

Research has long shown that most diets are plagued by a sad reality — when they end, the people on them almost always gain most or all of the weight back. But the new study offers hope for a possible way to avoid this pitfall.

Best of all, it essentially involves giving yourself a break.

For the study, published this month in Nature's International Journal of Obesity, 51 obese men between 25 and 54 were split into two groups. The first group followed a strict diet that involved slashing their calorie intake by a third of their needs (something called the "energy restriction" phase) for just over 3 and a half months.

The second group followed the same diet, but every two weeks they would take a break from it and go back to eating enough calories to meet their needs (the "energy balance" phase, in the researchers' parlance). The dieters who took breaks stuck to their interval plan for nearly 7 months — twice as long as the plain old dieters — but wound up with the same amount of strict diet time.

At the end of the study, the men on the diet-break-diet plan lost 47% more weight than the men who stuck to the traditional diet. More importantly, they also kept more of the weight off.

"Interrupting energy restriction with energy balance "rest periods" may ... improve weight loss efficiency," the researchers wrote in their paper.

Overriding the body's drive to hold on to fat

Losing weight can often feel like an uphill battle. There's some science that suggests that when we try to coax our bodies into healthy eating, our bodies fight back.

Research shows that people who've lost significant amounts of weight produce fewer of the hormones that make them feel full and more of the hormones that make us feel hungry. There’s also evidence that the metabolism slows down, perhaps because strict dieting convinces the body that it is starving, leading it to run as efficiently as it can and burn the fewest calories possible.

But the new study suggests it may be possible to trip those wires.

The clue to this possibility was in the last phase of the study, Krista Varady, a professor of nutrition who studies another type of dieting for weight loss known as intermittent fasting, told Newsweek.

Towards the end of the interval dieters' eating plan — around the time where most dieters stop losing or even sometimes regain weight, also known as the "dieting plateau"— the men in the study were still shedding pounds.

"Somehow they’re kind of keeping the body on its toes," she said.

Another potential advantage of the interval plan is that it could be easier to maintain than a traditional diet. While it might sound like a minor problem, sticking to a diet, something nutritionists call "diet adherence," is really important when it comes to losing weight and keeping it off.

For a recent study published in the Journal of the American Medical Association, out of 160 adults who tried one of four popular diets, more than half of the participants in one group dropped out before the study ended.

Andy Bellatti, a registered dietitian and the cofounder of Dietitians for Professional Integrity, told Business Insider that it's something he sees all the time with the people he works with, suggesting that a more sustainable weight loss plan involves incremental, long-term changes that someone can stick to for life.

"I know many people who’ve gone on some kind of crash diet for a week and lost a bunch of weight and a few months later they’re back to square one," said Bellati.

Instead of encouraging his clients to try something extreme, he advises taking small steps toward weight loss that can be maintained for the long haul. "I'd say 9 times out of 10 the people who change slowly and do manageable goals are the people who 3 years out still have success," he said.

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Clinic Compare, a British clinic comparison website, has put together a ranking of the most unhealthy countries in the world.

Using data from the World Health Organization (WHO), the CIA World Factbook, and the World Lung Association, the company analysed 179 countries, looking at alcohol and tobacco consumption per person, per year, as well as the prevalence of obesity.

The rankings for each factor were combined to give each country an overall score in order to determine which population has the unhealthiest lifestyle.

Eastern Europe dominated the top 10 most unhealthy countries, while Oceania came out as the "fattest region in the world." Scroll on to see the 20 most unhealthy countries in the world, ranked from best to worst.

20. Ukraine. The country took joint eighth place for alcohol consumption — each resident consumes the equivalent of 12.8 litres of pure alcohol every year.

19. United Kingdom. The UK ranks 19th for unhealthiness, with its residents being the ninth heaviest drinkers in the world.

18. Romania. On average, each resident smokes 1,619 cigarettes per year.

We already know that modern Western diets are loaded with added sweeteners (even our bread has excess sugar in it). With obesity numbers skyrocketing and the nutritional science community oscillating between sugar, fat, and carbs as the scapegoat du jour, it's hard to know what exactly is safe to eat. 

There are a lot of myths surrounding the effects sugar has on our health. But even though humans need glucose to survive, it's no secret that the exorbitant amount of sugar found in everyday foods like processed snack foods, canned food, and soft drinks have become too much for our bodies to handle.

We've rounded up 10 of the scariest effects a sugar-rich diet can have on your overall health, with expert input from Dr. Jennifer Haythe, a cardiologist at Columbia Presbyterian Hospital in New York; Rebecca Lee, a registered nurse and founder of RemediesForMe.com; and Colette Heimowitz, a nutritionist at Atkins Nutritionals, Inc. who has worked with celebrities like Kim Kardashian.

Weight gain

Multiple studies have linked the consumption of sugary foods and drinks to weight gain. Research published in the "American Journal of Clinical Nutrition" in 2011 confirmed a "positive association"between drinking soft drinks regularly and the rising obesity epidemic.

"Sugar-sweetened beverages, particularly soda, provide little nutritional benefit and increase weight gain and probably the risk of diabetes, fractures, and dental caries," the researchers concluded.

Your body needs glucose to survive, but when you consume more than you need, what happens?

"When you consume more sugar than the body can use, the body converts it into fatty acid and stores it for future use in adipose fatty cells, such as the hips, thighs, arms, and stomach," Lee said. 

Tooth decay

Sugar does not actually cause cavities, contrary to popular belief. However, the waste product (acid) caused by sugar interacting with the surface of your teeth will cause cavities. So if you're not watching what you eat (or ignore regular dental cleanses), you could be looking at a mouth full of decay.

Skin problems

We know the idea that eating chocolate causes acne is an old wives' tale, but can sugary foods really cause issues for your dermatological health?

Scientists have recently made the connection between consuming dairy and foods with high glycemic indexes (aka sweet foods) with skin problems.

"Research has substantiated the role of specific foods, such as dairy products, as well as dietary patterns, including the high glycemic load diet typical of the Western diet,"a 2014 study published in the Journal of Clinical and Aesthetic Dermatology said.

Special thanks to John Gunstad, professor with the Department of Psychological Sciences at Kent State University, for speaking with us about his cutting-edge research on how losing weight affects brain function. Following is a transcript of the video. 

Here’s what losing weight does to your body and brain.

During the first week, you may find it easy to lose weight by simply switching to a healthier diet. But as your metabolism adjusts, you won’t burn as many calories as you used to.

So losing additional weight will become harder.

Making matters worse, as the fat melts away, you’ll start to experience an increase in appetite. After a meal, fat cells release a hormone called leptin into the bloodstream.

This surge in leptin levels signals to your brain you’re full and should stop eating. But with less overall fat, people who lose weight show a measurable dip in leptin.

Brain scans of obese patients who had lost 10% of their body weight revealed that less leptin leads to increased activity in regions of the brain that control our desire to eat.

The result isn’t just an increased appetite but an even stronger urge to eat fatty, high-calorie foods, because your brain is trying to restore the body’s leptin levels to normal. 

However, fighting that early impulse to gorge on pizza and donuts is worth it in the long run.

Besides the decreased risk of heart disease, hypertension, high cholesterol and type 2 diabetes, scientists studying overweight people discovered that losing just one pound of body weight reduces four pounds of pressure on knee joints.

Losing excess weight also reduces strain on the blood vessels, increases blood flow to the brain, and boosts overall brain function.

Several studies have shown that people who underwent weight-loss surgery saw an improvement in memory, concentration, and problem-solving skills in as soon as three months.

Plus, brain scans indicate that people who lost weight and kept it off for nine months reacted differently when shown images of high-calorie foods than before they lost the weight.

The brain regions that process reward, motivation, and taste didn’t react as strongly, whereas the areas that promote overall self-control had a boost in activity.

So fighting those cravings early on might make them easier to control later. Turns out — like anything else — losing weight can get easier with practice.

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• Dozens of scientific studies suggest that eating fat isn't linked to weight gain.
• Aaron Carroll, a pediatrician and professor of pediatrics, says it's perfectly OK to eat butter, cream, nuts, and avocados.
• Instead of eating low-fat products, Carroll encourages people to eat less sugar, which studies have linked to weight gain and obesity.

"Eat fat, get fat" has been the conventional wisdom guiding American diets for the past two decades. Yet more and more research suggests that thinking is dangerously misguided.

"There is one thing we know about fats,"Aaron Carroll, a professor of pediatrics at the Indiana University School of Medicine, writes in his new book, "The Bad Food Bible: How and Why to Eat Sinfully."

"Fat consumption does not cause weight gain. To the contrary, it might actually help us shed a few pounds."

That means that foods like buttery avocados, rich salmon, and savory nuts should have a place in your diet. If you banned them as part of the low-fat dieting craze of the 1990s, it's time to bring them back.

The evidence lies in studies that have compared people on low-fat, high-carb diets with people on low-carb, high-fat diets. Time and time again, the research reveals that people who restrict their intake of fatty foods do not lose weight or gain other health benefits. In contrast, people who eat diets high in fat but low in refined carbohydrates like white bread and white rice tend to lose weight and see other health benefits as well.

To doctors and dietitians, these findings suggest that the real villain when it comes to weight gain isn't fat but rather added sugar and refined carbohydrates that get quickly broken down into sugar.

Low-fat diets don't make people thin

A large analysis, published in August in the journal The Lancet, compared more than 135,000 people on low-fat and low-carb diets in 18 countries. The researchers found that low-fat diets were more likely to be linked with death from all causes and found a higher likelihood of heart attacks and heart disease. People on low-carb diets, on the other hand, had significantly lower risk of both of these outcomes.

"Global dietary guidelines should be reconsidered in light of these findings," the researchers wrote in the paper.

Several other recent studies of people on low-fat eating plans have shown similar results. An eight-year trial involving almost 50,000 women put roughly half of them on a low-fat diet, and found that those women didn't see any decrease in their risk of breast cancer, colorectal cancer, or heart disease. Plus, they didn't lose much weight, if any.

"Bottom line? The evidence in favor of a low-fat diet is very thin, whereas the evidence for the benefits of certain fats is mounting," Carroll writes.

The body needs fat to function

The body requires fat to run properly.

Fat is essential for blood clotting and muscle movement. It's a required ingredient for building cell membranes (the shells that house each of your cells) as well as the protective shields around your nerves. Finally, fat helps us absorb vitamins and minerals from the foods we eat.

When we're not eating fat, we tend to eat more refined carbs and sugar, both of which have been strongly linked to weight gain and obesity.

A review of 50 studies on diet and weight gain published in the journal Food and Nutrition Research found that, on average, the more refined grains someone ate (like white bread and white rice), the more weight they tended to gain over the study period. By contrast, the more whole-grain foods someone ate (like whole-wheat bread and brown rice), the less weight they tended to gain.

Part of the problem is that refined carbs and sugar can encourage overeating.

"It's definitely easiest to overdo it with drinks, refined carbs, foods that have added sugar or are highly processed — those are things that we just tend to keep going,"Cara Anselmo, a nutritionist and outpatient dietitian at New York's Memorial Sloan-Kettering Cancer Center, told Business Insider.

Eat more fish, avocados, nuts

Still, some fats may be healthier than others.

For a recent study published in the Journal of the American Medical Association, researchers tested what happened when people swapped a small portion of the calories they got from saturated fat (which is most often found in meat and dairy products) with calories from unsaturated fat.

Doing so appeared to be linked with numerous benefits, including a reduction in the risk of death and conditions like heart disease and several neurodegenerative diseases.

"Not all fats are created equal," Harvard nutrition professor Frank B. Hu, a lead author on the study, told The New York Times. "We should eat more good ones from fish and avocados, instead of animal fats," he said.

According to a health blog maintained by the Harvard Medical School, healthy fats include those from nuts, fish, and olive oil — called mono- and polyunsaturated fats. The unhealthy ones are trans fats found in processed foods, and saturated fats "fall somewhere in between."

Overall, the take-home message is simple: Eating fat won't make you fat, but overdoing it on sugar will.

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NOW WATCH: 5 'healthy' breakfast foods that have more sugar than a glazed donut

• A new Harvard study projects that more than 57% of today's kids will be obese by their 35th birthday.
• Skyrocketing obesity rates around the globe are being blamed for higher cancer rates.
• Researchers say too much screen time and bad diets are largely to blame.

More American kids than ever are expected to carry a heavy load into adulthood.

In a study being published Thursday in the New England Journal of Medicine, researchers at Harvard's school of public health extrapolated future obesity trends based on thousands of children's current heights and weights. They estimate that nearly 6 in 10 kids in the US today will be obese by age 35. 

"When we look at trends in weight gain over the past 40 years, its not too surprising that we're heading in this direction," lead study author Zachary Ward told Business Insider.

Still, the projection is quite a jump from the current obesity rate, which hovers between 35-40% for 35-year-old adults. Overall, The Centers for Disease Control and Prevention estimates that roughly 38% of American adults can be classified as obese.

Ward said that the younger kids are when they develop obesity, the harder it it is for them to become healthy adults.

Increased screen time and bad diets are two of the reasons that rates are on the rise, he said. Ward's team at Harvard is researching new ways to prevent childhood obesity, like serving healthier snacks, limiting kids' screen time, and cutting sugary drinks like juices at nursery schools. 

"Children have already gained enough excess weight in young childhood that it puts them on a trajectory that's really hard to change as they grow older," Ward said. 

The obesity epidemic has been growing around the world for decades, but rates in the US have been climbing faster than any other country. Between 2003 and 2014, obesity rates in American kids aged 2-5 actually decreased from 13.9% to 9.4%. But rates in the other age groups have remained stable or continued to rise.

"Unhealthy foods are cheaper and they're everywhere; if you go to any store, you can buy a candy bar at the checkout but not a piece of fruit," Andy Bellatti, a registered dietitian and the cofounder of Dietitians for Professional Integrity, told Business Insider earlier this year.

Just earlier today, the United States Department of Agriculture relaxed nutrition rules for school meals, so cafeterias are now allowed to serve more processed breads, fewer whole grains, and more flavored milks. They can also add more sodium to kids’ breakfasts and lunches.

Obesity is measured by comparing height and weight, a metric known as 'Body Mass Index' or BMI. A BMI score of '30' or higher is generally considered obese. (A person who is 5 feet 9 inches tall and weighs in around 203 pounds would likely be considered obese, which is a step up from 'overweight.') 

Recent research has also shown that obesity is carcinogenic: A new report in The Lancet this week blames high BMI for 3.9% of all cancer cases worldwide, or more than half a million cases. 

SEE ALSO: This one ingredient is making a lot of Americans fat

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NOW WATCH: Here's what losing weight does to your body and brain

Maintaining a healthy weight can seem difficult at times, but it's worth the effort. Here's how gaining weight changes your body and brain, and not necessarily for the better. Following is a transcript of the video.

How gaining weight affects your body. You'll experience some changes, even where you don't expect. The weight you can see is only half the story. You also gain weight inside your body, around your organs. This fat, called visceral fat, gets in the way of metabolism hormones. The result is a terrible cycle where you, end up digesting food slower, which makes gain weight faster. 

Fat also makes the body more resistant to insulin. This can increase your risk of Type 2 diabetes. The larger your body is, the higher your blood pressure will be, since your heart needs to pump harder to circulate blood. This also increases the risk of stroke. Even visible fat can be dangerous. If you have fat stored around your neck, it can compress your airway. This makes breathing difficult and may lead to sleep apnea. Sleep apnea is a disorder that can lead to a greater risk of, high blood pressure, heart problems, Type 2 diabetes, and even death. 

Carrying extra weight also compresses joints, increasing the risk of osteoarthritis. Losing just 5% of your body weight can lower risks like heart disease. You can get there by making fruits and vegetables half your diet, and limiting yourself to lean proteins. Tip the scales on obesity now, before the damage is done.

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The unhealthiest states in the country all lie in the southeast US.

For the 28th year in a row, the United Health Foundation has ranked America's states based on factors including obesity, air pollution, and poverty. Massachusetts made the top of the list as America's healthiest state, while Mississippi was declared the unhealthiest.

Here's a map, with the healthiest states in light blue and the least healthy in dark blue.

Looking at data from the Centers for Disease Control and Prevention, the American Medical Association, and the Census bureau, the rankings took into account everything from obesity and smoking to community and environmental factors, such as child poverty and air pollution, to public policies like immunizations, and health outcomes like cancer deaths and diabetes.

Massachusetts ranked the healthiest state for the first time in the ranking's 28-year history. "Massachusetts’ strengths include the lowest percentage of uninsured at 2.7% of the population, a low prevalence of obesity and a high number of mental health providers," the report said. 

It was followed by Hawaii, Vermont, Utah, and Connecticut to round out the top five healthiest states.

At the same time, the UHF noted some troubling trends: premature death (that is, deaths that occur before an older age) rate and the drug death rate have both been increasing.

Here's the list of the 10 unhealthiest states, according to the report.

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41. Georgia has among the least physically active states, some of the highest child poverty rates, and a relatively high percentage of uninsured people. On a more positive note, Georgia was among the states with the least drug overdose death rates.

42. Kentucky, which rose in the rankings from 45 in 2016, has a high prevalence of smoking, along with the highest rate of cancer deaths. Kentucky also had the second highest rate of drug deaths, next to West Virginia. The state also has one of the lowest uninsured rates in the US.

43. Oklahoma, which also rose in the rankings from 2016 when it came in at 46, has a high cardiovascular death rate. Oklahoma also was among the states with the highest uninsured rate, while having a relatively high number of mental health providers.

• Holiday weight gain is tough to avoid, but there are plenty of things you can do to stay lean this winter.
• Instead of avoiding rich and savory foods that are high in fat, you should be avoiding refined carbs.
• Refined carbs are quickly turned into sugar in the body and have been tied with weight gain and obesity.

If you're concerned about putting on a few pounds this season, those rich, savory foods like cheesy dips, grilled salmon, and guacamole probably are not the ones you should be avoiding.

Instead, keep an eye out for huge portions of refined carbs like white rice, which the body quickly turns into sugar.

Dinner rolls, stuffing, and flour tortillas all fall into this category. Because they're so low in fiber and protein, they'll only fill you up for a short period of time. Refined carbs also lurk in dozens of processed foods, including granola bars, baked goods, pizzas, and pastas. Still, this doesn't mean you should ban these foods from your repertoire completely — just keep in mind that when you help yourself to a serving of them, you might want to keep it small and make room for more fish, veggies, and whole grains instead.

Overindulging on something like biscuits once is OK, but doing it consistently for months or years can wreak havoc on your health. Diets high in refined carbs have been repeatedly tied to outcomes like weight gain and obesity.

A review of 50 studies on diet and weight gain published in the journal Food and Nutrition Research found that on average, the more refined grains someone ate (like white bread and white rice), the more weight they tended to gain over the study period.

Some health experts think the problem with refined carbs has to do with the way we label them. After all, "refined" carbs sound like something you'd want to have on your plate. But Roxanne B. Sukol, a Cleveland Clinic physician and the medical director of its wellness enterprise, says we should start calling them "stripped" carbs instead —because they've been "stripped of all their nutrition."

The easiest way to steer clear of refined carbs

The easiest way to avoid refined carbs is to simply cook with or choose their whole grain versions. Instead of white rice, choose brown. Rather than white dinner rolls, opt for whole grain ones.

Whole grain carbohydrates aren't bad for you, and because they are rich in fiber, protein, and other nutrients, we tend not to overeat them like we do with "stripped carbs."

"People need to understand there are nutritious carbohydrates," Sukol tells author and chef Michael Ruhlman in the book "Grocery: The Buying and Selling of Food in America." Brown rice, wheat bread, fruits, veggies, and loads of different beans and legumes are all good options and contain what Sukol calls a healthy "fiber matrix."

In fact, whole grains are a chief component of some of the healthiest diets. US News and World Report describes plant-based diets featuring whole grains and vegetables as their foundation as "good for the environment, your heart, your weight, and your overall health."

SEE ALSO: Why you should stop eating white rice, according to a physician

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• It's impossible to directly compare the health effects of diet and regular soda, since we have far more research on the regular kind.
• The studies we do have suggest regular soda is linked with obesity and weight gain, while diet soda hasn't been strongly tied to any negative health outcomes.
• For that reason, Aaron Carroll, a pediatrician and professor of pediatrics, says it's fine to drink diet soda occasionally — but never the regular varieties.

Just how bad is your Diet Coke habit?

Probably not as unhealthy as you think. And swapping it for the regular stuff won't do you any favors.

"If I have to choose between diet drinks and those with added sugar, I'll go with the diet,"Aaron Carroll, a professor of pediatrics at the Indiana University School of Medicine, writes in his new book, "The Bad Food Bible: How and Why to Eat Sinfully."

The existing science on diet soda hasn't gotten the golden seal of approval that comes after extensive studies in humans. The research we do have is mostly in mice, but so far it suggests that the artificial sweeteners in soda are not overwhelmingly bad for our health.

On the other hand, extensive studies about human consumption of regular soda reveal an overwhelming link to two unhealthy outcomes: weight gain and obesity.

Comparing these two scenarios makes the choice between diet soda and regular soda clear, according to Carroll.

"There's a potential — and likely very real — harm from consuming added sugar. There is likely none from artificial sweeteners," he writes.

Still, dozens of seemingly damning scientific studies on diet soda and the artificial sweeteners it contains have been published over the last decade. Research has linked saccharin to cancer, and found evidence that people who regularly consume diet drinks are heavier than people who don't.

But Carroll says every one of those studies was riddled with enough errors not to be taken seriously. The way they were communicated to the public made it look like they were far more conclusive and severe than they really were, he wrote.

Research tying artificial sweeteners to cancer was done in rats who were vulnerable to cancer

In the 1980s, any product containing saccharin, the zero-calorie sweetener sold under the brand name Sweet'N Low, was required to carry a frightening warning label: "This product contains saccharin, which has been determined to cause cancer in laboratory animals."

Out of roughly 50 studies of rats fed saccharin — in amounts far beyond what a normal person would consume on a daily basis — only one experiment found that it seemed to cause cancer. But the rats in that study were a specific kind of rat that often become infected with a bladder parasite, Carroll explains in his book. The parasite leaves them extra vulnerable to cancer.

Carrol writes that the conclusion people should have drawn from all those studies is: "Rats are more vulnerable to side effects from saccharin than are people, for whom there's no clear evidence of risk."

Instead, artificial sweeteners everywhere have gotten a bad rap. Many were shocked by the recent news that President Donald Trump drinks roughly a dozen Diet Cokes per day. Of course, doing anything to excess is probably not a good idea. But dozens of further studies have failed to find any link between saccharin and cancer in humans, despite lingering skepticism.

"Public perception, once turned against any food, is very hard to change," Carroll writes.

The study linking diet drinks to dementia also found a link between regular soda and dementia

Other recent studies link diet drinks to even scarier-sounding health outcomes, including research published this spring suggesting that diet soda could cause dementia.

But that study was only one of a pair of studies looking at beverage consumption and brain issues. The second found a connection between drinking regular soda and brain shrinkage. More importantly, both studies fall into a category of research commonly found in food and beverage science called "observational" research.

Observational studies follow large groups of people over long periods of time and don't control for the variables they are testing. As a result, these kinds of studies can tell us if there's a connection between two things, but they can't tell us if one thing necessarily causes the other. In many cases, a link researchers observe between two things is later found to be caused by an external thing that no one accounted for.

The jury is still out on whether any external factor played a role in the studies about drinks and dementia. For now, there is no definitive research that tells us that sugary drinks cause brain shrinkage or that diet drinks cause dementia.

Plenty of research links regular soda to disease

Plenty of large, well-done studies link sugary drinks like sodaand juice to weight gain, obesity, diabetes, and heart disease in human beings.

One of them was a large review of 50 years' worth of studies published in the American Society for Clinical Nutrition. It found "strong evidence for the independent role of the intake of sugar-sweetened beverages, particularly soda, in the promotion of weight gain and obesity in children and adolescents."

Another paper written by seven experts in public health, nutrition, and economics describes the links between sugary drinks and America's obesity problem even more strongly:

"The science base linking the consumption of sugar-sweetened beverages to the risk of chronic diseases is clear," the authors concluded.

With this in mind, Carroll appears justified in his choice of diet soda over regular.

"When it comes to sugar and artificial sweeteners, the evidence is as strong as can be: the former is much worse for you than the latter," he wrote.

SEE ALSO: A professor of medicine explains why eating fat won't make you fat — but sugar will

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NOW WATCH: We boiled soda to see how much sugar is inside

• Bill O'Reilly tweeted on Tuesday that he thinks clothing sizes have gotten smaller, encouraging people to buy bigger sizes.
• In fact, with the rise of vanity sizing, the opposite is true.

Former Fox News host Bill O'Reilly thinks he found a culprit for his shrinking shirts. Clothiers using less fabric, he posited on Twitter, is surely the cause of shirts feeling tighter.

Unexpectedly, the replies were merciless.

In reality, it's highly unlikely that O'Reilly's new shirts are smaller than before. He says that it's a stealthy move on the part of the clothing makers to save fabric, but a few extra inches of fabric saved wouldn't account for the loss of sales and returned items a drastic change in size would cause. Materials like cotton are a relatively small portion of the price of clothing when labor, shipping, and design costs are taken into account. If there are any differences in the sizing, it's more likely O'Reilly's old shirts are just a bit stretched out compared to the new.

Clothes have actually gotten bigger over time. Vanity sizing, more common in women's clothing where a certain size has extreme variance among brands, has also struck men's clothing.

A size 30 pair of pants can actually measure 31, 32, or even 33 inches around, depending on where you're buying it. A study by Esquire found that a size 36 pair of pants could measure all the way up to 41 inches around. Others have corroborated the claims — vanity sizing is real, claims one Buzzfeed contributor post.

From the retailer's point of view, it makes sense. They're better off lying to you than causing you to worry about your waistline. It's a bet that you'll be so pleased you fit into a size "30" pair of pants, you'll purchase them immediately.

As retailers try to appeal to the broadest possible number of people, it's unlikely clothes would shrink as obesity continues to rise.

So, unfortunately for O'Reilly, it's unlikely that his shirts are getting smaller — he's just gotten bigger.

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• The authors of this article are researchers who study why diets fail.
• They encounter a lot of people who don't want to believe that dieting doesn't work.
• Many times, these people are thin and have never had to diet themselves.
• Below, they explain why "Naturally Thin Nicky" has it wrong.

Diets do not work.

The scientific evidence is clear as can be that cutting calories simply doesn’t lead to long-term weight loss or health gains.

We suspect most dieters have realized this by now too. And yet, here they are again, setting the same weight loss goal this year that they set last year.

The only people who don’t seem to appreciate this are people who have never dieted. It’s particularly hard for them to believe because it doesn’t square with their own eating experiences.

Take Nicky, for instance. She eats sensibly much of the time, with some junk food here and there, but it doesn’t really seem to affect her weight. She’s not a dieter. She is Naturally Thin Nicky, and it’s not surprising that she believes what she sees with her own eyes and feels in her own body. Nevertheless, Nicky has it wrong.

We are researchers who have been studying why diets fail for a long time. We have seen that diet failure is the norm.

We have also studied the stigma that heavy people face, and witnessed the blame game that happens when dieters can’t keep the weight off. From a scientific perspective, we understand that dieting sets up an unfair fight.

But many Nickys we’ve encountered – on the street, in the audience when we give talks, and even fellow scientists – get confused when we say dieting doesn’t work, because it doesn’t square with their own observations.

An unfair fight

Nicky thinks she’s thin because of the way she eats, but actually, genetics play a huge role in making her thin. Nicky gets all the credit though, because people see the way she eats and they can’t see her genes.

Many heavy people wouldn’t be lean like Nicky even if they ate the same foods in the same quantities. Their bodies are able to run on fewer calories than Nicky’s, which sounds like a good thing (and would be great if you found yourself in a famine).

However, it actually means that after eating the same foods and using that energy to run the systems of their body, they have more calories left over to store as fat than Nicky does. So to actually lose weight, they have to eat less food than Nicky. And then, once they’ve been dieting a while, their metabolism changes so that they need to eat even less than that to keep losing weight.

It’s not just Nicky’s genetically given metabolism that makes her think dieting must work. Nicky, as a non-dieter, finds it really easy to ignore that bowl of Hershey’s Kisses on her co-worker’s desk. But for dieters, it’s like those Kisses are jumping up and down saying “Eat me!” Dieting causes neurological changes that make you more likely to notice food than before dieting, and once you notice it, these changes make it hard to stop thinking about it. Nicky might forget those chocolates are there, but dieters won’t.

In fact, dieters like them even more than before. This is because other diet-induced neurological changes make food not only taste better, but also cause food to give a bigger rush of the reward hormone dopamine. That’s the same hormone that is released when addicts use their drug of choice. Nicky doesn’t get that kind of rush from food.

And besides, Nicky is full from lunch. Here again, dieters face an uphill battle because dieting has also changed their hormones. Their levels of the so-called satiety hormone leptin go down, which means that now it takes even more food than before to make them feel full. They felt hungry on their diets all along, but now feel even hungrier than before. Even Nicky’s regular non-diet lunch wouldn’t make dieters full at this point.

Where’s your willpower?

People see Nicky and are impressed with her great self-control, or willpower. But should it really be considered self-control to avoid eating a food when you aren’t hungry? Is it self-control when you avoid eating a food because you don’t notice it, like it or receive a rush of reward from it?

Anyone could resist the food under those circumstances. And even though Nicky doesn’t really need willpower in this situation, if she did need it, it would function quite well because she’s not dieting. On top of everything else, dieting disrupts cognition, especially executive function, which is the process that helps with self-control. So dieters have less willpower right when they need more willpower. And non-dieters have plenty, even though they don’t need any.

And of course, even if Nicky were to eat those tempting foods, her metabolism would burn up more of those calories than a dieter’s metabolism.

So Nicky is mistakenly being given credit for succeeding at a job that is not only easy for her, but easier than the job dieters face.

The cruel irony is that after someone has been dieting for some time, changes happen that make it hard to succeed at dieting in the long run. It is physically possible, and a small minority of dieters do manage to keep weight off for several years. But not without a demoralizing and all-encompassing battle with their physiology the entire time.

It’s easy to see why dieters usually regain the weight they lose on their New Year’s resolution diet, and we have the following suggestions for when that happens: If you are a Nicky, remember the self-denial these dieters have subjected themselves to and how little they were eating while you treated yourself to decadent desserts. Be impressed with their efforts, and grateful that you don’t have to attempt it.

If you are a dieter, remind yourself that you aren’t weak, but that you were in an unfair fight that very few win. Change your focus to improving your health with exercise (which doesn’t require weight loss), and resolve to choose a different New Year’s resolution next year.

Traci Mann is the author of “Secrets from the Eating Lab" and a professor of psychology at the University of Minnesota. A. Janet Tomiyama is an associate professor of psychology at the University of California, Los Angeles. 

Traci Mann has received grants from the National Institutes of Health, NASA and the USDA.

A. Janet Tomiyama receives funding from the National Science Foundation and the Robert Wood Johnson Foundation.

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NOW WATCH: What gaining weight does to your body

• Public Health England has issued new advice for how many calories adults should eat per day.
• Men and women should aim for 1,800 calories per day, which is considerably less than official guidelines of 2,500 for men, and 2,000 for women.
• PHE is issuing the advice because many people don't account for calorific drinks when calculating their daily calorie intake, and go over the recommended guidelines.
• Critics say the advice is a panic measure in response to an increasingly overweight population.

For ages, calorie guidelines have been the same — men should consume about 2,500 calories per day, and women should have 2,000.

But Public Health England (PHE) has issued new guidelines to urge adults to reduce the amount of food they eat.

Both men and women should aim for 1,800 calories over their three meals a day, PHE says, as people in the UK are consuming more than we should. About 200-300 calories more, in fact.

The idea behind these new recommendations is that you only count the calories in food, and ignore those from drinks. Calories can be split over the course of the day: 400 at breakfast, 600 at lunch and dinner, then 200 for snacks.

PHE's still officially advises that you hit 2,000 or 2,500 calories a day overall, depending on your gender. But those numbers include drinks as well as food, and the new advice is intended to encourage people to think more carefully about how many calories they consume through food alone.

PHE also wants to work with popular chains to persuade them to offer healthier meals, as part of a campaign expected to launch in March 2018 called "One You."

"Calorie guidelines have not changed — it's still 2,000 a day for women and 2,500 for men. Adults consume 200-300 too many calories a day, leading to weight gain and health issues," said a PHE spokesperson. "Our new OneYou campaign will give tips on managing calories for main meals so that by the end of the day, including snacks and drinks, total calories are closer to the guidelines."

However, not everyone is convinced. Speaking to the Daily Mail, Tam Fry from the National Obesity Forum said the new guidelines are a "panic measure" to get the public to understand they are eating too much.

"Portion sizes are getting bigger and people are mindlessly eating them just because they are there," he said. "The idea is sound because we are eating too much, but my feeling is the thresholds are too low."

Christopher Snowdon, head of lifestyle economics at the Institute of Economic Affairs think-tank, told the Daily Mail that the original calorie guidelines have been established for decades, and there is nothing wrong with them.

"Public Health England's latest calorie guidelines are not based on evidence and are essentially a lie designed to manipulate people into eating less," he said. "This nanny-state agency makes it up as it goes along."

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