Designer Diets That Downsize The Danger

For millions of overweight Americans, yo-yo dieting is worse than an annoyance. Studies at Yale and Harvard Universities show that people who lose and gain back weight die earlier than those who keep their weight constant. Now, an Agriculture Dept. researcher has a simple way to help people avoid dangerous weight swings.

In a study of young women up to 50 pounds overweight, USDA research chemist Nancy L. Keim found that the higher a person's initial level of free fatty acids--stored fat released into the bloodstream by exercise--the more fat she could expect to lose in a three-month period. Keim developed an equation that should allow a doctor to calculate fat loss from a diet--and prevent people from trying to lose more than they can realistically keep off. But further tests are needed on all greatly overweight people--and on men, who process fat differently from women--before the equation is ready.

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