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Earlier this month a video titled "Dear Fat People" went viral for all the wrong reasons. The video starred a kind-of-famous-on-YouTube comedian named Nicole Arbour, who decided to use her platform to address the millions of people who are not as skinny as she is. She wanted to let overweight people know just how disgusting she thinks they are.

In the video, Arbour scolds obese individuals that "Crisco is coming out of their pores." She also tells them, “you are killing yourself.” The overarching message: Being obese is entirely in a person’s control, and the fact that they are overweight is a clear sign of weakness.

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In 'Dear Fat People,' Nicole Arbour shouts at people for being overweight.

The backlash against the video was swift—for a time, YouTube even disabled Arbour’s account—and the response highlighted just how far we’ve come in tolerating (or not tolerating) fat shaming, at least in such a cruel and obvious way. But it also highlighted how far we've come in understanding obesity. We know more today than ever before about how the disease works.

Well, some people do. Despite all the campaigns to #StopFatShaming, studies have shown that the population at large still shows prejudice against overweight people—which describes 68% of the United States population. (Thirty-five percent of America is considered obese.) These prejudices manifest in a belief that whatever struggles an overweight person endures, well, it's his or her own fault—and he or she deserves no sympathy until they change.

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"People mistakenly think that obesity is a behavior," Nikhil V. Dhurandhar, chair of the department of nutritional sciences at Texas Tech University and president of The Obesity Society, told me over the phone. In fact, he said, it's a "serious and complex disease." This thinking leads people to adopt a “you brought this on yourself” mentality, he said, which is not helpful or fair. "You don't choose obesity. It's like diabetes. It's not really under your control."

On the heels of Arbour’s video—which the comedian later claimed was meant to be taken as satire (uh huh)—we looked into the latest science on what actually causes humans to become obese. Here’s what everyone should know before the next fat shamer strikes.


You probably know that obesity is a growing epidemic in this country and around the world. And yet, our genes determine 40 to 70 percent of our body mass index (BMI), according to several weight loss experts. Given that human genetics haven't changed much in the past century, why the sudden widening of our collective waists?

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"The thing that has changed in the last 40 years is environment," said Lisa Neff, a professor of endocrinology, metabolism, and molecular medicine at Northwestern's Feinberg School of Medicine. Neff is referring to the introduction of sedentary lifestyles coupled with a rise in cheap, fast, processed foods, which together have created a perfect storm of conditions contributing the obesity epidemic.

"Our genes load the gun and the environment pulls the trigger," said Neff.

Basically, our bodies still operate like they did back in those hunter-gatherer days when we always needed to be ready for famine. The body's main objective back then was to store fat just in case. Today, the body stores excess fat even when we don't want or need it to. However—and this is where it gets interesting—some people store fat differently based on their genes.

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"What we know now is that there are things like brown fat that actually burns calories," said Neff. For the non-biology majors, our bodies can store extra calories as either white and brown fat. White fat, which is more common, is that fat you don't want (think muffin tops). Brown fat cells, however, are packed with mitochondria that burn energy and create heat, which in turn burns calories. Studies have shown people with more brown fat also have lower BMIs.

Neff said new research has also pointed to an "obesity gene"—the FTO gene—that works as a "master switch" for fat storage, telling your body when to store extra calories as brown fat rather than white fat.

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Obesity researchers believe that people who become obese have a variance of the FTO gene that tells their body to store calories as white fat—so they don't burn extra calories as efficiently as someone whose FTO gene works differently. "If they eat an extra cookie, it may end up on their hips," Neff told me, whereas a person who stores more calories as brown fat can eat that same cookie and burn it off easily. This gene could eventually prove key to combatting obesity—when scientists tinkered with the gene in mice who were fed a high-fat diet, the critters were able to resist weight gain.

Even for people who have the right variance of this obesity-fighting gene, the human body tends to work against us when trying to lose weight. We can blame this annoying reality on the region of the brain called the hypothalamus, which controls weight management.

The hypothalamus "sets" a certain minimum weight for our bodies, and will fight like hell to keep us from dipping below that weight, Neff explained. Unfortunately, however, it doesn't prevent us from gaining weight—because, well, there might be a famine later!

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Making matters worse, if we keep weight on for a long period of time, the body will reset its "weight set point" and work to maintain the new minimum weight. The moment you start trying to shed those pounds, your body kicks into famine mode. Losing weight—even if it's weight that should be lost—"sets into play the same metabolic and hormonal functions as starvation," said Neff. The body releases hormones to make you feel more hungry and less full in an effort to keep the weight on, and well, the rest is dieting hell history.

Neff acknowledged how frustrating this cycle can be. "The changes in the environment came in the last 40 years," she said, "but we’re still stuck with the genes that worked 2,000 or 3,000 years ago."


So we know that environment and genetics influence our weight. But the "cause" of obesity, like the "cause" of cancer, is complex, said Dhurandhar. "Just because the picture of a disease looks similar doesn't mean there is one cause," he said. "Obesity has multiple contributors, multiple factors."

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Some of the dozens of factors have been identified? A person may have a medical condition that causes her to gain weight (like polycystic ovary syndrome). She may be taking medication that increases weight gain, such as steroids, hormone replacement therapy, or certain antidepressants like Paxil. She may have an underlying mental disorder that affects eating habits, or she may have a food addiction. She may be suffering from a physical injury or handicap that prevents exercise or movement. Or her socioeconomic status limit her access to healthy food.

In some people obesity may even be caused by a virus. Dhurandhar's recent research has focused on viruses that effect weight. He told me about a virus called adenovirus-36 (or Ad-36), which can increase fat cell production in some people and make fat cells fatter, potentially leading to the disease.

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While diet and lifestyle certainly play a role in influencing a person's weight, assuming that a person's eating and exercise habits are the reason—or the only reason—for their obesity is misguided, say the experts. Some people face a much harder battle to keep off the pounds, or suffer from extenuating circumstances that make healthy living challenging.

"People feel that because everybody eats, they can comment on it," said Dhurandhar, "but just because you eat everyday doesn't mean you understand nutritional science."


In her fat-shaming rant, Arbour says, "I really hope this bomb of truth makes you want to be healthier." After talking to obesity experts, however, it's clear obesity is not simply a "calories in / calories out" disease—and yelling at someone to lose weight doesn't help.

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Dhurandhar said he hears stories about these kinds of unhelpful "truth bombs" being hurled at his patients all the time. "Some people tend to think, 'All I'm going to do is to tell someone that their BMI is this, and magically, they are going to start to losing weight," he said, stressing that this approach simply does not work.

"Who needs to tell them this? All of us have mirrors, all of us know where we should be. The sad reality is that people know what their BMI is. They may be doing something about it, and they may not get anywhere. Treatment has not been successful in many individuals, and those who are successful don't always maintain that body weight," he said. "How unfair it is to point the finger at someone, and say, 'Hey, why don't you do something about it.'"

(Of course, pop culture is filled with examples of weight-loss professionals doing just that, which reinforces obesity myths. On the NBC reality show The Biggest Loser, for example, coaches shout at contestants while dramatically slashing their calorie intake and upping their exercise—attributing their obesity mostly to bad habits. Many contestants gain the weight back after the show ends, however, suggesting the underlying cause was never treated.)

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Michael Jensen, a professor of endocrinology, diabetes, metabolism, and nutrition at the Mayo Clinic, told me that most of his patients are aware their weight is a problem. Yet even with that awareness, they struggle to lose the pounds. "Some have surgery and they still can't make the behavior changes they need to," he said. "But that means there could be something [else] going on there: behavioral, hormonal, or psychological."

Notably, Jensen said he's seen other patients who have a much easier time losing weight. So what's the difference between the two groups? "I'd love to know the answer to that question," he told me. Until science provides those answers, he advises "not to lump everyone together who has a weight problem."


In order to really combat obesity, experts agreed that we need to work to stop the disease before it starts—on both an individual and societal level. "When you look at other things, like smoking and seat belts, it wasn’t [just] individual efforts," said Jensen. "We agreed as a society that this is important."

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First Lady Michelle Obama has made it her mission to teach kids healthy eating and exercise habits with her Let's Move! campaign, which may help young people make smarter choices about the contributors to obesity that are in their control. Obesity experts also advised that restaurants list calorie counts on their menus and cut down portion sizes—and that companies incorporate exercise and wellness programs into the work day and provide access to healthy food.

As individuals, if we find ourselves struggling, the experts recommended seeking out medical and psychological help—and offering help to those who are struggling. None of their recommended tactics include fat shaming.

Hey, Arbour—you catch all that?

Taryn Hillin is Fusion's love and sex writer, with a large focus on the science of relationships. She also loves dogs, Bourbon barrel-aged beers and popcorn — not necessarily in that order.

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