Low GI Bests Low Fat in Preserving Metabolic Rate

BOSTON--A low glycemic load diet may lower resting metabolic rate less than a low fat diet during weight loss, according to a study published in the November issue of the Journal of the American Medical Association (292, 20:2482-2490, 2004).

In the randomized parallel-design study, 39 overweight or obese young adults between18 and 40 years of age followed an energy-restricted, low-glycemic load or low fat diet. Prior to and subsequent to 10 percent weight loss, subjects were assessed for resting energy expenditure in the fasting state, body composition, cardiovascular disease risk factors and self-reported hunger. The low glycemic load diet decreased resting energy expenditure to levels less than the low fat diet. Participants following the low glycemic load diet reported less hunger than those adhering to the low fat diet. Subjects receiving the low glycemic load diet also showed greater improvements in insulin resistance, serum triglycerides, C-reactive protein and blood pressure than those following the low fat diet. Both groups showed similar changes in fat and lean body mass.

The researchers concluded changes in diet can produce changes in physiology and body weight, and noted reduction in glycemic load may aid in the prevention or treatment of obesity, cardiovascular disease and diabetes mellitus.