A high-GL diet may help maintain weight loss

Today's column is an example of how research can set out to find out one thing and discover something completely different along the way.

One of the components of weight management that scientists are interested in is the concept of "self-efficacy" - or the feeling that one is competent or capable of performing a task. Researchers at Tufts University decided to investigate whether counseling intended to lead to greater self-efficacy (Appetite 2014(80):204-211), combined with a high or low Glycemic Load (high-GL or low-GL) diet, would help individuals lose weight or maintain that weight loss.

Glycemic Load is based on the Glycemic Index, which is a standardized measure that measures how much a food will raise one's blood sugar levels after eating it. Glycemic Load is the practical application of the Glycemic Index: it is calculated based on the Glycemic Index of a food as well as the amount of available carbohydrates contained in that food, so the Glycemic Load can be calculated for different sizes of servings of food, an entire meal, or everything one eats in a day.

For this study, 42 clinically overweight but otherwise healthy men and women between the ages of 20 and 42 received twice-weekly counseling sessions intended to lead to greater feelings of self-efficacy around weight loss. At the same time, they were randomly assigned to a high-Glycemic-Load diet or a low-Glycemic-load diet. For the first six months of the study, all food was provided to the participants, then for the second six months of the study, the participants chose, shopped for, and cooked their own meals according to training they'd been given about their high-GL or low-GL diet and the number of calories they were assigned to eat.

Both groups lost about the same amount of weight, and the GL level of their diets did not appear to affect the participants' levels of self-efficacy. Almost as an aside, the researchers note that those on a low-GL diet regained some weight during the second six months of the study, while those on a high-GL diet maintained their initial weight loss.

What this means for you

Despite their improved feelings of self-efficacy, those on a high-GL diet maintained their weight loss while their colleagues in the low-GL group regained weight. That suggests that a high-GL diet is more sustainable: they found it easier to maintain a high-Glycemic-Load diet. People have often argued that a low-Glycemic-Load diet is better for you in terms of managing hunger (Bite, 03/12/08) or risk factors for heart disease (Bite, 07/26/06), but it's still the quality of calories that count - a Milky Way bar is low Glycemic Index, after all.

First posted: June 18, 2014