Metabolic rate makes keeping weight off difficult for some

Dear Doctor K: I heard about a recent study that explained why the “Biggest Losers” had trouble keeping the weight off. Can you explain? over time. For example, our brain sends signals that lower our metabolic rate when we lose weight. Why would that be? It’s because our ancestors tens of thousands of years ago were often hungry, often going days without food. The brain could slow the potentially dangerous loss of weight by telling the body to burn fewer calories.

Our genes today are not very different from those of our ancestors long ago. But in the developed nations, we’re almost all well-fed. More of us are overweight than underweight.

The genes that protected our ancestors actually cause problems for us.

The recent study followed contestants in the “Biggest Loser” competition six years after the competition ended. Their average weight before the competition was 328 pounds. After the 30week competition, it was 200 pounds. As expected, their metabolic rate had dropped as they lost weight.

The surprise: Six years later, their average weight was 290 pounds — but their metabolic rate had not gone back up as they regained those 90 pounds. As a result, they still were not burning many calories, making it harder not to regain weight.

The study offers one explanation for why weight loss during dieting usually cannot be maintained. As research improves our understanding of what controls the metabolic rate, we may develop tools for helping achieve and maintain a healthy weight.