When researchers compared a low-fat diet, a very low-carbohydrate diet, and a low-glycemic-index diet among persons trying to maintain weight loss, they found that the low-glycemic diet proved to be the best option; supporting the body’s calorie burning rate while also being heart healthy.
In this study, Dr. David Ludwig and his colleagues at Boston Children’s Hospital examined which diets best support health and metabolism after weight loss. Each of the study's 21 adult participants (ages 18-40) first had to lose 10-20% of their body weight, and after weight stabilization, completed all three of the following diets in random order, each for four weeks at a time. The low-fat diet, emphasized whole grain products and a variety of fruits and vegetables and was composed of 60% of calories from carbohydrates, 20% from fat, and 20% from protein. The low-glycemic index diet treatment was made up of minimally processed grains, vegetables, healthy fats, legumes and fruits, with 40% of calories from carbohydrates, 40% from fat and 20% from protein. Low-glycemic-index carbohydrates digest slowly, helping to keep blood sugar and hunger hormones stable after meals. The third diet treatment, a low-carbohydrate diet modeled after the Atkins diet, was composed of 10% of daily calories from carbohydrates, 60% from fat, and 30% from protein.
Researchers then measured how many calories participants on each of the diets burned. They found that persons on the low card diet burned about 150 more calories than those on the low-glycemic diet and nearly 300 more than those on the lowfat diet.
While the Atkins-type diet stimulated the greatest calorie burn, it had negative effects on chronic disease risk factors including an increase in stress hormones and inflammation. Indeed another recent study by Swedish researchers found that women who regularly follow an Atkins-style diet have a 28% increased risk for heart disease and stroke.
The results of this article have been widely reported as ground breaking in the media. However, in an editorial accompanying the publication of these results, Dr. George Bray stressed caution in interpreting the results from this short-term relatively small study. "There are some interesting physiological responses in this study, but translating this information for possible long-term results is difficult to do. Adherence is an important element. If a diet helps you adhere better, that will help you to manage your weight, but, in longer-term studies none of these diets has proven better than any other at weight management over the long-term." In a recent New York Times interview, highly respected longtime obesity researcher Dr. Jules Hirsh pointed out that while there is evidence that proteins take somewhat more energy to digest, fats require less energy to be stored as fats. And, because high fat and high protein diets cause initial water losses, the findings that calorie burning was higher in these diets was likely an artifact of how these values were assessed rather than actual differences in metabolic rates while on the diets of different macronutrient composition.
What to do: This study’s results support a diet higher in fat than is traditionally recommended but actually in line with what persons following a healthy diet usually achieve. While substituting fats (which do not effect blood sugar), for carbohydrates helps to moderate blood sugar increases after a meal, it is also important to choose heart healthy fats and not increase total caloric intake. In this study caloric intake was carefully controlled so that even with a relatively high fat intake, total caloric intake did not increase. However, in real world situations, this can prove tricky as gram per gram fats have more than twice as many calories as carbohydrates and proteins.
Overall, any diet that eliminates fat, carbohydrates, or protein is inherently unbalanced. A mixture of all the macronutrients is needed to nourish our bodies and feel satisfied. Modern diets tend to be high in refined carbohydrates such as sugar and white flour as well as unhealthy meat and dairy fats. While being mindful of caloric intake it is important to choose foods high in nutritional quality including whole food carbohydrates, healthy fats from plant and fish sources, and proteins that are low in fat or from oily fish.
SOURCES:
Cara B. Ebbeling et al. Effects of Dietary Composition on Energy Expenditure During Weight-Loss Maintenance. JAMA, June 27, 2012 DOI: 10.1001/jama.2012.6607
Pagona Lagiou et al. Low carbohydrate-high protein diet and incidence of cardiovascular diseases in Swedish women: prospective cohort study. BMJ. 2012; 344: e4026. doi: 10.1136/bmj.e4026
http://www.nytimes.com/2012/07/10/health/nutrition/q-and-a-are-high-protein-low-carb-diets-effective.html
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