Popular reality television program The Biggest Loser debuted on NBC in 2004 and ran there for more than ten years. In it, obese people competed with one another via strenuous physical tasks and ate a diet low in calories to see who could drop their body weight by the greatest percentage. Prior research on The Biggest Loser competitors demonstrated that recovering lost weight does not bring the metabolism back to its pre-weight loss levels. Instead, it significantly slows down after major weight reduction.1 This means that persons who have dropped a significant amount of weight must maintain an extremely low calorie consumption. One competitor on the show dropped 239 pounds and reached a weight of 191 pounds, but six years later, after gaining back 100 pounds of the weight he had lost, he needed to eat 800 calories each day to stay at his weight. In other words, the Biggest Loser diet plans didn’t go as planned!
Recent studies on the relationship between exercise and metabolism show the Biggest Loser diet plans didn’t work like they thought they would
The Biggest Loser results can be explained and interpreted in light of an energy conservation model in a more recent study by the same researcher. According to Dr. Kevin Hall’s “constrained model of human energy expenditure,” the contestants’ metabolisms slowed down significantly as a result of the prolonged, intense physical activity they underwent. This was done to lower their metabolic rates and, as a result, minimize changes in total energy expenditure. In other words, to preserve energy balance, their bodies automatically made compensatory modifications.
In fact, the contestants who maintained the most weight loss six years after the competition actually had the most metabolism adaptation, which is particularly interesting given that the degree of metabolism reduction at the conclusion of The Biggest Loser competition was not related to contestants’ subsequent weight regain. This shows that the change in lifestyle, namely the sharp increase in physical activity shown in those who maintained the largest weight loss, is what led to the metabolic adaption.2 For people attempting to sustain major weight loss, the compensatory mechanisms fortunately do not totally negate lifestyle adjustments, making it possible to maintain big weight loss.
What insights towards weight loss have we gained from observing The Biggest Loser weight gain ?
Together, these studies on The Biggest Loser contestants have taught us that, while immediate decreases in resting metabolic rate are associated with severe calorie restriction during active weight loss, the larger, more long-lasting metabolic adaptation that occurs later is associated with significant increases in sustained physical activity.
Results from the National Weight Control Registry, which was founded in 1993 to identify traits of people who successfully maintain a healthy weight, have long shown the importance of physical activity for weight control. We don’t yet understand how long-term increases in physical activity help weight loss maintenance despite the long-term compensatory decline in resting metabolic rate. According to Dr. Hall, the reason for this can be related to the way exercise reduces appetite.
But as is always the case, more research is required to completely understand the connection between body composition, exercise, energy balance, and weight maintenance. In the meanwhile, we should continue to heed the well-researched recommendations to consume wholesome foods in moderation, stay away from processed foods, and exercise frequently in order to maintain a healthy body weight.