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Earlier this week, The New York Times published a detailed story on the stunning results of a six-year weight-loss study that show exactly why losing weight — and keeping it off — is so hard for most people. 

Researchers followed 16 of the season 8 contestants from the Biggest Loser for six years after their tenure on the show and found that not only did most of them gain the weight they had lost during the show back, but also that their metabolisms slowed to such a degree that it "was as if their bodies were intensifying their effort to pull the contestants back to their original weight," NYT reports. In fact, as the scale kept climbing, each contestant's metabolism kept plummeting. 

What does this mean? Essentially, that biology might play a bigger role in weight loss than previously believed. There are some limitations to this study (the small sample size and the lack of a control group, for example), but Michael Schwartz, an obesity and diabetes researcher at the University of Washington (he was not involved in this particular study), tells NYT that the results of this study are game-changing. 

“The key point is that you can be on TV, you can lose enormous amounts of weight, you can go on for six years, but you can’t get away from a basic biological reality," he said. “As long as you are below your initial weight, your body is going to try to get you back.”

Here are some more key takeaways about weight loss from the article: 

1. The Biggest Loser style of weight loss isn't very effective. The show's contestants follow an incredibly rigorous diet and fitness regime — one participant Danny Cahill told NYT he exercised for seven hours per day while on the show — and then return to their daily lives, jobs, families, and previous commitments to find that they're unable to sustain that level of working out for long. 

2. Your hormones play a big role in weight loss. At the beginning of each season, the contestants on the BL undergo medical testing to ensure they can handle the intense workouts. Researchers have found that though each contestant starts out with normal levels of leptin — a hormone that can affect cravings — they end the season with almost no leptin in their body, which might explain why they had an easier time losing weight during the show and keeping it off shortly after. However, as contestants gained the weight back over time, their leptin levels increased — and this could explain why many of the contestants report battling severe cravings and feelings of hunger in follow-up studies. 

3. There's no perfect formula for weight loss. It's not as simple as just eating fewer calories and exercising more, though, of course, those two things are important to anyone who's trying to lose weight. Instead, every expert interviewed in the NYT piece agreed that this study proves that we need to approach obesity, weight loss, and weight maintenance differently and stop equating weight loss with the amount of willpower a person has. With at least one-third of the adult population in the U.S. is obese, it's unlikely that every single one of them has no willpower. It would make sense that biology plays a role, too.