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Short Answers to Hard Questions About Weight Loss

Almost everyone who has ever dieted knows how hard it is to keep the weight off. And almost everyone, including many scientists, has wondered what works. An article on Monday about what happened to contestants from “The Biggest Loser” television show is a vivid illustration of the problem. Although there is no magic formula for weight maintenance, here are answers to some questions that arise over and over.

Are you more likely to maintain weight loss if you lose weight slowly?

That is the advice dieters often get, but studies have not found that to be the case. For example, a recent Australian study, funded by the Australian National Health and Medical Research Council and the Sir Edward Dunlop Medical Research Foundation, randomly assigned 204 obese people to subsist on just 450 to 800 calories a day for 12 weeks, or to cut a more modest 400 to 500 calories a day from their diets over 36 weeks. The goal for both groups was a 15 percent weight loss. Three years after the study began, almost everyone had regained the weight they lost, despite counseling on diet and exercise. There was also no difference in the levels of two hormones, leptin and ghrelin, that drive hunger. The main difference between the groups was that more people in the rapid weight loss group lost at least 12.5 percent of their weight (80 percent, compared with 50 percent in the slow loss group) and fewer dropped out (3 percent, compared with 18 percent).

To maintain weight loss, should you avoid snacks?

Although it seems to make sense that snacks can pack on the pounds, studies that randomly assigned people to snack or not have failed to confirm this, and even observational studies have not found evidence that snacks undermine weight loss.

If you build muscle with exercise, including weight lifting, will you be able to maintain a higher metabolism?

Muscle burns more calories than fat, so it might stand to reason that the more muscle you have the faster you will burn calories. But it turns out that building muscles has almost no effect on resting metabolism, which determines how many calories a person burns when at rest. The reason is that any muscle you add is small compared with the total amount of skeletal muscle on your body. And most of the time that muscle is at rest. (You can’t go around flexing your biceps nonstop.) Muscles have a very low metabolic rate at rest. One researcher calculated that if a man weighing about 175 pounds lifts weights and puts on about 4½ pounds of muscle — a typical amount for men who lift weights for 12 weeks — he will burn an extra 24 calories a day, the amount in a couple of Life Saver candies. Continue to the original article.

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