How much is our weight really in our control?

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.

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.

“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?

“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.

Our genes load the gun and the environment pulls the trigger.

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.

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!

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.”

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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.”

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.