A report in Circulation: Cardiovascular Quality and Outcomes, an American Heart Association journal, aimed to find out which diets work best in the long term. That means, after you’ve gulped water for weeks and dropped water weight, what really works to keep the pounds off after a year? And what are the effects on your heart?
It is an important question because about 70 percent of American adults are either overweight or obese. We're constantly looking for that next great thing that will help us drop weight and feel better about ourselves.
Researchers looked at four popular diets — Atkins, Weight Watchers, South Beach and Zone. They were compared to “usual care,” which includes low-fat diets, behavioral weight loss intervention, nutritional counseling or self-help materials. On those, the average person lost anywhere from 1.8 to 11.9 pounds after the first year.
They found that:
1. Weight Watchers dieters lost an average 7.7 to 13.2 pounds after one year, but partially regained some weight two years after starting the diet in one study.
2. South Beach dieters did not have a difference in weight loss in a study that compared the program to usual care. Participants in this study were both severely obese and had undergone gastric bypass surgery.
3. Results from trials on the Atkins diet were inconsistent but...
4. Another study found that dieters on Atkins, Weight Watchers, the Zone and "usual care" specifically experienced modest weight loss at one year. Atkins dieters lost an average 4.6 to 10.3 pounds; Weight Watchers participants lost an average 6.6 pounds; Zone dieters lost an average 3.5 to 7 pounds. Those on usual care lost on average 4.85 pounds. There were no differences in how those improved cholesterol, blood pressure, blood sugar levels or other cardiovascular risk factors.
"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," he said, adding that more studies are needed.
Weight Watchers and Atkins seemed to be short-term winners.
"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 Dr. Mark J. Eisenberg, M.D., M.P.H., a professor of medicine at Jewish General Hospital/McGill University in Montreal, Quebec, Canada.
Another report released this fall in the Journal of the American Medical Association (JAMA), summed up a meta-analysis of 48 randomized clinical trials of branded diets (including the four in the aforementioned study), including more than 7,200 overweight and obese adults with a median age of 46 years.
At six months after starting the diets, those on low-carbohydrate diets lost 19 more pounds than those who were not on a diet, while those on low-fat diets lost 17 more pounds than those on no diet. At a year, about two to three pounds of that difference was gone; also at that time, researchers didn't find a difference between low-fat and low-carb diets.
In other news, Dr. Barry Sears, who founded the Zone diet with his book Enter the Zone, just released The Mediterranean Zone, which is a combination of principles from his original Zone diet along with beneficial aspects of the Mediterranean diet integrated. It would be interesting to see other newer, popular diets — paleo or gluten-free, anyone? — researched.
"The health benefits of any diet is best measured by its ability to lower inflammation," said Dr. Sears.
"This is why the dietary guidelines of the Joslin Diabetes Center at Harvard Medical School for treating obesity and diabetes are very similar to the Zone diet," he said. Reducing inflammation, as opposed to simply losing weight, is the key to reducing cardiovascular risk.
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