Popular commercial diets can help you lose some weight in the short term, but keeping the weight off after the first year and the diet's impact on heart health are unclear, according to a study published in Circulation: Cardiovascular Quality and Outcomes , an American Heart Association journal.
Nearly 70 percent of American adults are overweight or obese - and therefore at higher risk for health problems such as heart disease, stroke, high blood pressure and diabetes. Whether a diet will be effective is an important public health question.
"Despite their popularity and important contributions to the multi-million dollar weight loss industry, we still do not know if these diets are effective to help people lose weight and decrease their risk factors for heart disease," said Mark J. Eisenberg, M.D., M.P.H., the study's senior author and Professor of Medicine at Jewish General Hospital/McGill University in Montreal, Quebec, Canada. "With such a small number of trials looking at each diet and their somewhat conflicting results, there is only modest evidence that using these diets is beneficial in the long-term."
After analyzing clinical trials on four popular diet plans -- Atkins, South Beach, Weight Watchers, and Zone -- that promote weight loss and improved cardiovascular health, researchers found:
The longest diet studies researchers analyzed lasted for two years, and results were only available for the Atkins or Weight Watchers diets. Those studies found dieters regained some of their weight over time.
To better understand the potential benefits from any one or all of these diets, researchers need to conduct large clinical trials directly comparing all four popular diets for long-term weight loss and changes in other heart disease risk factors, he said.
"A broader lifestyle intervention, which also involves doctors and other health professionals, may be more effective," Eisenberg said. "This also tells doctors that popular diets on their own may not be the solution to help their patients lose weight."
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Co-authors are Renée Atallah, M.Sc.; Kristian B. Filion, Ph.D.; Susan M. Wakil, M.D.; Jacques Genest, M.D.; Lawrence Joseph, Ph.D.; Paul Poirier, M.D., Ph.D.; Stéphane Rinfret, M.D., S.M.; and Ernesto L. Schiffrin, M.D., Ph.D. Author disclosures are on the manuscript.
The Canadian Institutes of Health Research funded the study.
Additional Resources
Is My Fad Diet Good For My Heart?
Recent study adds weight to the low-carb vs. low-fat debate
The American Heart Association's Diet and Lifestyle Recommendations
Overall heart-healthy diet is more important than occasional indulgences
Doctors urged to treat obesity as a disease under new guidelines
Follow AHA/ASA news on Twitter @HeartNews
Follow CircCVQO on Twitter: Circulation: CVQO@CircOutcomes