(14-07-07) Low-Glycaemic-Load Diet Yields Better Results in Some Obese People

A low-glycaemic-load diet produces more weight loss and more loss of body fat than does a low-fat diet in obese young adults who have high insulin concentrations on oral glucose tolerance testing.
In contrast, a low-glycaemic-load diet yields the same results as does a low-fat diet in subjects who do not have high insulin concentrations 30 minutes after a dose of oral glucose, according to Dr. Cara B. Ebbeling and her associates at Children?s Hospital Boston. These findings indicate that some of the variation in the results of previous weight-loss trials may be attributable to differences in subjects? insulin responses, the researchers said in the May 16 issue of the Journal of the American Medical Association.
Dr. Ebbeling and her associates conducted a randomised controlled trial to determine whether subjects? insulin secretion would affect their loss of weight and of body fat on two different diets. The subjects were 73 obese men and women aged 18-35 years who underwent oral glucose tolerance testing at entry into the study.
In the trial, 36 subjects were randomly assigned to consume low-glycaemic-load foods such as nonstarchy vegetables, legumes, and temperate fruits. They were told to avoid high-glycaemic-load foods such as refined grains, starchy vegetables, fruit juices, and sweets. Their goal was to obtain 40% of energy from carbohydrates; 35% from healthful fats such as those found in nuts, seeds, and oils; and 25% from protein.
The other 37 subjects were assigned to consume low-fat grains, vegetables, fruits, and legumes. This group was told to avoid added fats and high-fat foods. Their goal was to obtain 55% of energy from carbohydrates, 20% from fat, and 25% from protein.
All subjects were expected to participate in a 6-month program of intensive intervention followed by 12-month follow-up. The intensive program involved 23 1-hour group workshops to foster the knowledge and skills needed to follow the respective diets, a 1-hour private counselling session, and 5 half-hour motivational phone calls.
There was no calorie-counting or target levels for macronutrient intake. Instead, subjects were instructed to eat only when hungry but before they felt famished, and to stop eating when they felt sated but before they felt stuffed.
Among subjects who had high insulin concentrations in response to the glucose tolerance testing at study entry, those in the low-glycaemic-load group lost weight more rapidly during the intensive intervention, achieved a greater overall weight loss, lost more body fat, and had better maintenance of the weight loss at 18-month follow-up than did those in the low-fat group.
Among subjects who didn?t have high insulin concentrations in response to the glucose tolerance testing, these measures did not differ between those on the low-glycemic-load diet and those on the low-fat diet, the investigators said (JAMA 2007;297:2092-102).
In terms of lipid response, HDL cholesterol and triglyceride levels improved more on the low-glycaemic-load diet than on the low-fat diet. Conversely, LDL cholesterol levels showed more improvement on the low-fat diet, they added


Source:Elsevier Global Medical News

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