The New York Times reports that taking weight off and keeping it off is likely to be even harder than previously imagined. People who lose 10 percent or more of body weight suffer a metabolic change that causes them to burn food more slowly, develop more efficient muscles, and suffer from increased food cravings. In other words, once you have put on the fat, it is very hard to go back to being skinny. And even when you take off weight, it is hard to keep it off. The Times describes the kind of vigilance that is necessary as follows:
There is no consistent pattern to how people in the registry lost weight — some did it on Weight Watchers, others with Jenny Craig, some by cutting carbs on the Atkins diet and a very small number lost weight through surgery. But their eating and exercise habits appear to reflect what researchers find in the lab: to lose weight and keep it off, a person must eat fewer calories and exercise far more than a person who maintains the same weight naturally. Registry members exercise about an hour or more each day — the average weight-loser puts in the equivalent of a four-mile daily walk, seven days a week. They get on a scale every day in order to keep their weight within a narrow range. They eat breakfast regularly. Most watch less than half as much television as the overall population. They eat the same foods and in the same patterns consistently each day and don’t “cheat” on weekends or holidays. They also appear to eat less than most people, with estimates ranging from 50 to 300 fewer daily calories.
The challenge may not be insuperable, but it clearly is a challenge.