Low Glycemic Diet Yields a Higher Burn Rate
Jackie Ballou MS, RD, LDN
“What diet should I choose to lose weight?” is by far the most commonly asked question I receive from clients, friends and family.
It’s no wonder people are confused about what to eat to manage their weight considering the number of conflicting nutrition messages we are exposed to on a daily basis.
From gluten-free and grapefruit diets, cookie diets to cleanses, many diets promise results, but what actually works? And more importantly, which type of diet helps prevent weight regain after loss?
While weight loss success is individual, a recent study published in the Journal of the American Medical Association offers some promising insights into how best to maintain lost weight.
The researchers looked at how three different diets, very low-carbohydrate, low-glycemic index, and low-fat affected participants’ energy expenditure, or total number of calories burned. The research also evaluated hunger levels after losing 10-15% of their body weight. The glycemic index ranks carbohydrate containing foods depending how they affect blood sugar after eating. High glycemic index foods like white bread, sweets and sugary drinks result in a rapid rise and fall in blood sugar, while low glycemic index foods such as most vegetables, fruits and beans more moderately affect blood sugar.
It is thought that one possible mechanism explaining why lost weight is so often regained is due to a resulting decrease in energy expenditure and an increase in feelings of hunger. These factors combined set the stage for weight regain after loss–you use less calories than before losing weight, plus you feel more hungry.
Twenty-one adults with overweight/obesity participated in the seven month-long study. Participants underwent energy expenditure testing among other tests at the beginning, during and at completion of the study.
After following a diet that resulted in a 10-15% weight loss, participants were randomly assigned to the three different diets. In random order, participants followed each of the diets for one month. During this phase of the study, goal was for participants to maintain their weight, thus each of the three diets contained the same amount of calories.
Researchers found that although the three diets contained the same amount of calories, participants’ energy expenditure differed, depending on diet. On average, when participants were on the very low-carbohydrate diet, their energy expenditure was 300 calories higher than when they were on the low-fat diet. The low-glycemic index diet also resulted in higher energy expenditure than the low-fat diet, although less so than the very low-carbohydrate diet. Researchers did not find any difference in self-reported hunger levels between the three diets. Although the very low-carbohydrate diet was advantageous in terms of higher energy expenditure, when participants followed this diet, body levels of markers of inflammation (an indication of stress) were also highest, compared with the other two diets. Study authors explained some research has demonstrated markers of inflammation may put people at risk for cardiovascular disease. Another disadvantage to a very low carbohydrate diet not sited in this study is the increased risk of depression and irritability.
This study demonstrates the low-glycemic index diet may result in increased energy expenditure after weight loss compared to a low-fat diet, without increasing markers of bodily stress as shown with the very low-carbohydrate diet. While the study points to the low-glycemic index diet as most beneficial for weight maintenance after loss, the evidence will be strengthened with more research in a larger population over a longer duration.
Bottom line, the study is promising for sustained weight loss with the low-glycemic index diet, but stay tuned for more research. Nutrition for weight loss, despite all the seemingly conflicting messages, is a young science, but thanks to well-designed research studies like this one, we are coming closer to evidence-based solutions that work.
Ebbeling CB, Swain JF, Feldman HA, et al. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance. Journal of the American Medical Association. 2012; 307(24): 2627-2634.