Forget the cabbage soup diet, the blood-type diet, the hormone diet and every other fad diet that may hit bookshelves at the start of each New Year. The diet that delivers optimal results – better health and lasting weight management – already exists.
On Tuesday, the Journal of the American Medical Association published the results of a study that determined which diet, among three classics: low-fat, low-carb or low glycemic, is the most effective. The study was designed, not to determine which diet offers the fastest results, but to assess which diet will minimize the struggle associated with maintaining weight loss.
In the past, studies have shown that people who lose weight must endure a dual struggle to maintain the loss because weight loss reduces the overall number of calories the body burns daily, also known as energy expenditure.
Twenty-one participants, aged 18 to 40 years old were required to consume a balanced diet with 45 percent of total calories coming from carbohydrates, 30 percent from fat and 25 percent from protein for three months. At the conclusion of three months, the dieters lost 10 to 15 percent of their total body weight.
Thirty days following the completion of the initial diet, the participants were divided into three groups: one on the low-fat diet, as recommended by the American Heart Association, one on the low-carb diet, similar to the Atkins diet and one on the low-glycemic index diet. Each group rotated between the three diets, testing each for one month.
At the completion of the study, lead author, Dr. David Ludwig told The Wall Street Journal, “The low-fat diet had the worst effect [on energy expenditure]. We should avoid severely restricting any major nutrient and focus on the quality of the nutrient.” His comment followed the review of results showing that participants on this diet experienced very low energy expenditure as well as increases in triglycerides and HDL cholesterol (the “good” cholesterol”.)
The low-carb diet yielded the largest increase in energy expenditure, approximately 300 more calories per day – in comparison to the low fat plan. However, the additional calorie burn also induced some unhealthy effects, including increases in the stress hormone, cortisol and an increase in C-reactive protein (CRP), an inflammation marker linked to an increased risk of heart attack, stroke and diabetes.
The true winner for long-lasting results and good health is the low-glycemic index diet. Energy expenditure for participants on this diet totaled around 150 calories per day without negatively affecting cholesterol levels or hormones.
The glycemic index (GI) is a value system established to measure the impact of carbohydrates on blood glucose levels. (There are books available for purchase that detail nearly every food on the market, websites to help you calculate the glycemic index of common foods or easy to follow instructions for simple calculation on your own.)
Processed carbohydrates and refined sugars make the list of high-glycemic foods, while non-starchy vegetables and fiber-rich foods are the stars of the list of low-glycemic foods. Foods with a GI of less than 55 are considered low GI foods, while foods with a GI of 70 or more are considered high.