BOSTON -- The most successful diet for weight loss is the one that patients will stick with, provided that it has a balance of protein, fats, and carbohydrates.
"Successful diets for weight loss can emphasize a large range of macronutrient intakes," Dr. Frank Sacks said at a symposium sponsored by the International Atherosclerosis Society.
"Diets should be made with foods that reduce the risk of cardiovascular events in and of themselves," added Dr. Sacks, professor of cardiovascular disease prevention at the Harvard School of Public Health in Boston.
In one study, a low-carbohydrate ketogenic (Atkins) diet produced a greater degree of weight loss over 6 months than did a low-fat diet. But the ketogenic diet was associated with more adverse events, including constipation, halitosis, myalgia, and headache (Ann. Intern. Med. 2004;140:769-77).
In a separate, 1-year trial comparing a low-carbohydrate Atkins-style diet with a low-fat diet, patients on the former lost weight more quickly during the first 6 months, but then began to gain it back. Patients on the low-fat diet had a steady and continual decline in weight over 1 year, with the two curves converging so that weight loss between the groups was similar at the end of the study (Ann. Intern. Med. 2004;140;778-85).
"You wonder if the curves are going to converge at some point, and is the tortoise going to catch up with the hare," Dr. Sacks said in commenting on that study.
Dr. Sacks and his colleagues took a different approach in a 2001 pilot study that compared a Mediterranean-style diet with moderate fat levels to a low-fat diet (Int. J. Obes. Relat. Metab. Disord. 2001;25:1503-11).
Dieters in both groups lost a mean of about 13.5 pounds within 6 months. But patients on the low-fat diet began to regain more weight, and at 18 months their mean weight loss was only about 6 pounds from baseline, while patients on the moderate-fat diet maintained a mean weight loss of 11 pounds from baseline. Only 20% of patients randomized to the low-fat diet were still on it 18 months later, compared with 54% of those randomized to the moderate-fat arm. In both arms, patients who dropped out had a net gain of 9 pounds over starting weight at 18 months, while those who stayed in the program--low-fat or high-fat--had a net loss of 11 pounds.
A common problem with comparative weight-loss trials is that there is no obvious pattern of results favoring a specific fat, carbohydrate, or protein content for weight loss. Also, many diets induce weight loss over 3-6 months, but the loss is not sustained for 1 or 2 years. In addition, up to half of all participants in some studies drop out, and study results may be influenced by the novelty of diets, marketing, or media attention, he said.
To try to cut through the background noise, Dr. Sacks and his colleagues conducted the 2-year PoundsLost study comparing four diets (N. Engl. J. Med. 2009; 360:859-73) The investigators randomly assigned 811 overweight adults to one of four diets, with targeted percentages of energy derived from fat, protein, and carbohydrates, respectively, of 20%, 15%, and 65%; 20%, 25%, and 55%; 40%, 15%, and 45%; or 40%, 25%, and 35%. Foods were similar among the four diets, and participants were offered group and individual weight-loss instruction sessions for the duration of the study.
At 2 years, there were no significant differences in weight loss between the 20% and 40% fat-content diets, 15% and 25% protein-content diets, or 35% and 65% carbohydrate diet. About 80% of all participants completed the study, and satiety, hunger, satisfaction with the diet, and attendance at group sessions were similar among all diet groups. The authors found that educational support was a strong predictor of weight loss, with each session attended associated with an average 0.2 kg weight loss. All of the diets improved lipid levels and fasting insulin levels.
"We feel these results have an optimistic message for people," Dr. Sacks said. "Successful diets for weight loss can be tailored to an individual's personal and cultural preferences to achieve long-term success. It's not so important to focus on particular contents of fat or protein, but more on what people feel comfortable with and can sustain for the long run."
Dr. Sacks reported that he has received consulting fees and/or performed contracted research for ISIS and Genzyme.
Osterweil, Neil. "Weight-loss diets best when matched to patient preferences." Internal Medicine News 42.14 (2009): 10. Academic OneFile. Web. 2 Dec. 2009.
Gale Document Number:A206804569
Disclaimer:This information is not a tool for self-diagnosis or a substitute for professional care.
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