Low-Glycemic-Load Diet Can Help Dieters Get Past Plateau

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Pereira MA, Swain J, Goldfine AB, et al.: Effects of a low-glycemic load diet on resting energy expenditure and heart disease risk factors during weight loss. JAMA 292:2482-2490, 2004.

What is the problem and what is known about it so far?

After they lose some weight, people often hit a point where it becomes harder to lose more weight. This is because as people lose weight, they actually burn fewer calories. So, the more weight a person loses, the fewer calories they burn.

Researchers wanted to find out if a diet low in carbohydrates that are easy to digest (a low-glycemic-load diet) is better at helping dieters keep losing weight than a low-fat diet. Low-glycemic-load foods include prunes, barley, beans, apples and other foods.

Who was studied?

Researchers studied 39 overweight or obese adults age 18 to 40. Each person had to lose 10% of his or her body weight at the beginning of the study to stay in the study.

How was the study done?

People in the study were put into two groups and given two different calorie-restricted diets: one low-fat and the other low-glycemic-load. On both diets, they were supposed to be able to lose 10% of their weight during a 6- to 10-week period.

Everyone stayed in the hospital for a short time. When people were released, they followed the diet on their own. They came to a clinic every day at the same time to be weighed, fill out a questionnaire, and eat lunch. Researchers also measured resting energy expenditure (the number of calories burned while resting).

All foods were carefully measured and prepared. Daily calories were divided among four meals: 25% breakfast, 30% lunch, 30% dinner, and 15% snack.

What did the researchers find?

The study found that people on the low-glycemic-load diet burned more calories, even at rest, than people on the low-fat diet. Also, people in the low-glycemic-load group reported less hunger than those in the low-fat group.

Although people in both groups lost about the same amount of weight, the low-glycemic-load diet had other benefits: less heart disease risk, lower insulin resistance, lower lipids, and fewer signs of inflammation.

What were the limitations of the study?

Portion sizes and calories were carefully controlled, which is not how people eat when they're not on a diet. It is not clear if people following these diets would have lost the same amount of weight if calories were not controlled.

What are the implications of the study?

A low-glycemic-load diet (or a diet low in carbohydrates that are easy to digest) may help overweight people keep losing weight better than a low-fat diet.

Dieters who have trouble keeping weight off, or who can't seem to lose beyond a certain point, may want to try a low-glycemic-load diet.