Two articles in the Sept. 2 Annals of Internal Medicine review and compare the low-carb and low-fat diets.
A low-carbohydrate diet is more effective for weight loss and reducing cardiovascular risk factors than a low-fat diet, the first article notes.
More than one third of American adults have at least one form of cardiovascular disease and cardiovascular disease causes one third of all deaths. Low-carbohydrate diets are a popular strategy for weight loss, but their cardiovascular effects are unknown, especially among diverse populations. To compare the effects of a low-carbohydrate versus a low-fat diet on body weight and cardiovascular risk factors, researchers randomly assigned 148 men and women without clinical cardiovascular disease and diabetes to follow a low-carbohydrate (less than 40g a day) or low-fat diet (less than 30 percent of daily calories from fat). All participants were classified as obese based on body mass index and just over half of the participants were black. Both the low-carbohydrate and the low-fat groups received dietary counseling at regular intervals but had no specific calorie or energy goals. At one year, both black and white participants on the low-carbohydrate diet had greater decreases in weight, fat mass, and other cardiovascular risk factors than those on the low-fat diet.
Rise in obesity is a substantial contributor to increased prevalence of diabetes
An increase in body mass index (BMI) over time is the most important factor contributing to the observed increase in diabetes prevalence since 1976, according to the second study. Diabetes is one of the most common and costly chronic disorders in the United States. Researchers analyzed data from five National Health and Nutrition Examination Surveys to determine the extent to which the increase in diabetes prevalence is explained by changing distributions of race/ethnicity, age, and obesity prevalence in U.S. adults. They found that the prevalence of diabetes nearly doubled from 1976 to 1980 and also from 1999 to 2004. During both time periods, diabetes prevalence increased more in men than in women. The increase of certain risk factors, including BMI, race and ethnicity, and age, coincided with an increased incidence of diabetes, with BMI being the greatest contributor among the three covariates. The researchers suggest that public health efforts should focus on interventions that address obesity. The increased prevalence of diabetes among men could not be explained by an increased BMI in men. Researchers suggest that future research should investigate what additional factors may contribute to the faster rise in diabetes in men than in women.
- L.A. Bazzano, T. Hu, K. Reynolds, L. Yao, C. Bunol, Y. Liu, C.S. Chen, M.J. Klag, P.K. Whelton, and J. He. Comparing Low-Fat and Low-Carbohydrate Diets. Annals of Internal Medicine, September 2014 DOI: 10.7326/P14-9029
- Lydia A. Bazzano, Tian Hu, Kristi Reynolds, Lu Yao, Calynn Bunol, Yanxi Liu, Chung-Shiuan Chen, Michael J. Klag, Paul K. Whelton, Jiang He. Effects of Low-Carbohydrate and Low-Fat Diets. Annals of Internal Medicine, 2014; 161 (5): 309 DOI: 10.7326/M14-0180
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