Anyone who has tried the South Beach Diet or any of the recent diets that regulate carbohydrate intake may be familiar with the concept of glycemic index. Glycemic Index (GI) is the concept in which different carbohydrates affect the body differently. Carbohydrates that have a high GI are easily processed by the body, and result in a spike in the blood glucose and insulin levels. This is believed to have a myriad of negative effects on the body, not the least of which are insulin resistance, diabetes, and weight gain. Foods with a low GI, are processed by the body at a slower rate and do not cause the spike in blood glucose or insulin. The GI concept was introduced to the world in 1981 by Dr. David Jenkins and his colleagues at the University of Toronto.
A group of researchers from the University of Sydney recently published the results from a randomized, controlled trial that compared relative effects of different GI-based diets on weight loss and cardiovascular risk. The study appeared in the Archives of Internal Medicine.1
Researchers put 129 overweight or obese young adults on one of four different diets. Diet 1 was high carbohydrate (55% of caloric intake), high GI, and average protein. Diet 2 was high carbohydrate, low GI, and average protein. Diet 3 was high protein (25% of intake), 45% carbohydrate intake of high GI carbs. Diet 4 was high protein, 45% carbohydrate intake of low GI carbs. All combinations reduced body-fat mass. But only Diet 2, the high carbohydrate, low GI diet reduced cardiovascular risk.
1. McMillan-Price, J., P. Petocz, et al. (2006). "Comparison of 4 diets of varying glycemic load on weight loss and cardiovascular risk reduction in overweight and obese young adults: a randomized controlled trial." Arch Intern Med 166(14): 1466-75.
