Alex Wong / Getty Images Michelle Obama in Washington, DC, in February 2013.

Michelle Obama, who has made fighting childhood obesity her signature issue, recently appeared on the NBC television show The Biggest Loser to encourage people to drink more water. Encouraging viewers to choose water over sugary drinks is a good thing. But the First Lady’s endorsement of this abusive show—and its enduring popularity as its 15th edition marks its mid-season finale—is indicative of all that is wrong about the broader “war on obesity.”

The show’s premise is that anyone can be thin if they work hard at it. Not only are fat people slothful and gluttonous, but—because obesity is a deadly and costly disease—they risk their own health and the economic health of the nation. Contestants describe themselves as “selfish” and as throwing their lives away; a trainer explains that if the contestants “want it bad enough, if they can change themselves mentally and emotionally right here, the rest will follow.” Over and over again, the show portrays being heavy as both a death sentence and a personal choice.

(MORE: If Obesity is a Disease, Why Are So Many Obese People Healthy?)

In fact, body weight is determined by a host of biological, genetic, and social factors, often beyond one’s personal control. According to a study published in the New England Journal of Medicine, 70 percent of the variation in people’s weight can be accounted for by genetic inheritance.

The extent of shaming on The Biggest Loser is extreme, but the general attitude that anyone can lose weight by applying themselves is pervasive. News reports on obesity overwhelmingly emphasize individual responsibility. A typical article will blame children’s weight gain on “lazy hours in front of the TV” rather than reading, playing board games, or engaging in other sedentary—but virtuous—activities.

There are health risks associated with higher body mass, the clearest being Type 2 diabetes, which becomes more likely with increased weight. But the association between weight and Type 2 diabetes is far from perfect—and it’s unknown whether being heavy causes diabetes, whether diabetes causes weight gain, or whether both conditions are caused by a third factor.

A 2008 study showed that a person’s weight is not a perfect predictor of other health issues. Almost a quarter of normal-weight people had abnormal metabolic profiles, while more than half of overweight people and almost a third of obese people had normal profiles. In other words, treating weight as a proxy for health could result in the under-diagnosis of more than 16 million normal-weight Americans and the over-diagnosis of almost 56 million overweight and obese Americans.

Meanwhile, there is growing evidence that our widespread societal anti-fat bias is taking a toll. Yale researchers have shown that weight discrimination in the United States has increased dramatically in the past decade and is now comparable to rates of reported racial discrimination, especially among women. Heavier women are less likely to be hired, to earn a higher salary, to marry, or to marry a higher-earning spouse compared to their similarly qualified thinner peers.

My colleagues and I have conducted research that suggests that exposure to moralizing messages promoted on shows like The Biggest Loser worsen anti-fat prejudice. We found that people who read a news report discussing an alleged obesity health crisis were more likely to agree with stereotypes of fat people as unlikable, untrustworthy, and less intelligent than thinner people. By aligning herself with The Biggest Loser, Michelle Obama further legitimizes anti-fat attitudes, and the ills they spread.

Moreover, discussing physical activity and nutrition solely as weight matters, instead of contributors to one’s broader health, is counterproductive. Given how difficult it is to lose weight, the First Lady should consider using her platform to promote a more constructive message: that people of all sizes can make positive nutritional and exercise changes.

This article first appeared Zocalo Public Square.