Your body doesn't want you to lose all that weight.
A study that followed 14 of the 16 contestants from Season 8 of "The Biggest Loser" six years after the season ended has detailed just how the body fights against efforts to keep off the pounds.
"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," Michael Schwartz, an obesity and diabetes researcher, explained to The New York Times. "As long as you are below your initial weight, your body is going to try and get you back."
The study, published by the medical research journal "Obesity," focused on resting metabolic rate (RMR), which slows with weight loss, and whether or not slowing of RMR persisted over long periods of time.
The study hypothesized that the degree of that metabolic adaptation would be correlated with weight gain. Virtually all of the contestants put significant weight back on in the last six years, but the troubling part for the researchers was that their RMR remained quite low, not returning to their pre-"Biggest Loser" levels.
Danny Cahill, who won Season 8, dropped from 430 pounds down to 191 pounds during the show. He is now back up to 295. But his metabolism now burns 800 fewer calories per day than would be typical for a man of his size, making it more difficult to maintain or reduce weight.
Dina Mercado had a similar experience. She was 248 pounds before "The Biggest Loser" and 173.5 pounds at the finale. She is now back up to 205, but is, like Cahill, burning calories at a reduced rate relative to her size. She should be able to metabolize an additional 437.9 per day.
The study concluded that "long term weight loss requires vigilant combat against persistent metabolic adaptation that acts to proportionally counter ongoing efforts to reduce body weight."