"Glycemic load" of diet has no effect on weight loss

When it comes to losing weight, the number of calories you eat, rather than the type of carbohydrates, may be what matters most, according to a new study.

The findings, published in the American Journal of Clinical Nutrition, suggest that diets low in "glycemic load" are no better at taking the pounds off than more traditional - and more carbohydrate-friendly - approaches to calorie-cutting.

The concept of glycemic load is based on the fact that different carbohydrates have different effects on blood sugar. White bread and potatoes, for example, have a high glycemic index, which means they tend to cause a rapid surge in blood sugar. Other carbs, such as high-fiber cereals or beans, create a more gradual change and are considered to have a low glycemic index.

The measurement of glycemic load takes things a step further by considering not only an individual food's glycemic index, but its total number of carbohydrates. A sweet juicy piece of fruit might have a high glycemic index, but is low in calories and grams of carbohydrate. Therefore, it can fit into a diet low in glycemic load.

However, the effort of figuring out what's an allowable carb might not be worth it, if the new study is any indication.

Principal investigator Dr. Susan B. Roberts, of Tufts University, Boston, and colleagues found that a reduced-calorie diet, whether glycemic load was high or low, was effective in helping 34 overweight adults shed pounds over one year.

Study participants who followed a low-glycemic-load diet ended up losing roughly 8 percent of their initial weight, as did those who followed a high-glycemic-load diet.

"The bottom line is that in this study we don't see one single way to eat that is better for weight loss on average," Roberts told Reuters Health. Of course, that doesn't mean "anything goes" as long as you're cutting calories."

A super-sized serving of French fries won't do any dieter any good, she noted.

Both diets her team used in the study were carefully controlled. For the first 6 months, participants were provided with all the food they needed, and both diets were designed to cut their calories by 30 percent while providing the recommended amount of fiber, limiting fat and encouraging healthy foods like fruits and vegetables.

The comparable outcomes suggest that, among healthy diets, no single one stands out as better, according to Roberts. So the focus should be on calories, rather than specific foods to avoid or include.

"Focusing on calories is something we need more of, especially when portion sizes are so absurd," Roberts said, referring to the portions served at so many U.S. restaurants.

This doesn't mean, however, that there's no place for diets that focus on glycemic load, according to the researcher. Some studies, for example, have found that low-glycemic index foods might help control blood sugar in people with type 2 diabetes.