Low-carbohydrate eating is more effective for heart health and weight loss than low-fat dieting, a new study finds. These outcomes counter the current U.S. Dietary Guidelines, which have promoted a low-fat diet for decades.
Today's publication of the first-ever Bayesian analysis of weight-loss dietary therapy, based upon data from 17 randomized-controlled trials of 1,797 obese and overweight participants, demonstrates superior weight loss and greater reduction in predicted risk of cardiovascular disease for participants following a low-carbohydrate diet rather than a low-fat diet.
The study, published in PLOS ONE, was conducted by Jonathan Sackner-Bernstein, MD, cardiologist and former senior official at the United States FDA, David Kanter, Georgetown Law School, and Sanjay Kaul, MD, MPH, Cedars-Sinai Medical Center in Los Angeles.
"The Bayesian approach provides insights that are not feasible with traditional meta-analysis and reveals the likelihood of an outcome, making it easier for a doctor or patient to understand the results more clearly. In this case, the Bayesian analysis shows us that a low-carbohydrate diet has a 99 percent probability of leading to greater weight loss, making the choice of how to eat much easier," said Dr. Sackner-Bernstein, the leader of the research analysis. "Although the study found a modest difference between each diet's weight loss and health outcomes, the study showed a higher likelihood that restricting carbohydrates is superior to restricting fat and it is important to consider low-carbohydrate guidance when making any dietary recommendations."
The number of overweight and obese Americans increased from 42.3 percent to 66.1 percent from 1971 to 2011, according to a recent statistical review of consumption in the U.S., whereas fat consumption dropped from 44.7 percent to 33.6 percent from 1965 to 2011 and carb consumption increased from 39 percent to 50 percent during the same period.*
"These statistics suggested a link between high-carbohydrate consumption and obesity on a societal scale and were the basis for conducting this analysis using data from randomized clinical trials, which are the types of studies accepted as the gold standard for learning whether a treatment makes a real difference," explained Dr. Sackner-Bernstein.
Each of the 17 trials included in the study were a randomized comparison between the effects of low-fat or low-carbohydrate diets on weight loss and cardiovascular risk factors. The study also applied the National Institute of Health's tool to predict risk of a heart attack or stroke, and showed that the low-carbohydrate diet was 98 percent more likely to lower those risks than a low-fat diet.
These findings apply the standards set for a low-fat diet as consuming 30 percent or less of calories from fat a day and for a low-carbohydrate diet as consuming 120 grams or less of carbohydrates a day, and are relevant to obese and overweight people without significant comorbidities.
Results also showed that while seven out of the 17 studies reported significant weight loss on a low-fat diet, seven of the trials showed statistically significant advantages for a low-carbohydrate diet and none showed a statistically significant advantage for a low-fat diet. In addition, predicted risk of cardiovascular disease, heart attacks and strokes were significantly reduced when following a low-carbohydrate diet.
"With the astonishing number of Americans suffering from obesity, our research findings on the positive implications of a low-carbohydrate diet on health will hopefully be taken into consideration when the U.S. Department of Health and Human Services and the U.S. Department of Agriculture complete their process of developing the 2015 Dietary Guidelines," said Dr. Sackner-Bernstein.
Atkins Nutritionals, Inc. supported the study, but did not participate in the study design, data collection, analysis or manuscript preparation.