Best Diet? The One You'll Follow

Study Shows Weight Loss Is Similar in Four Types of Diets

Reviewed by Elizabeth Klodas, MD, FACC on February 25, 2009
From the WebMD Archives

Feb. 25, 2009 -- If you are trying to lose weight, just pick a diet, any heart-healthy diet, and stick to it.

It doesn't matter much if it's high in protein or not, high in unsaturated fat or not. You can expect to lose about the same amount of weight on any weight loss plan, according to a new study which found that the best diet is the one you will follow.

"Find a diet type that is comfortable for you," says study researcher Frank M. Sacks, MD, a professor of cardiovascular disease prevention at the Harvard School of Public Health. As long as the diet is heart-healthy, and calorie-controlled for your needs, he says, you will lose weight if you stick to it. It also helps to get support in the form of loved ones or an organized group, he found.

In his study, he didn't find a significant difference in weight loss regardless of the diet type. In each of the four groups, participants averaged a 13-pound loss at the six-month mark.

The study is published this week in The New England Journal of Medicine.

Comparing Diets

For years, debate has raged about whether a diet that focuses on protein, carbs, or fat is best for weight loss. So Sacks and his colleagues randomly assigned 811 people to one of four diet plans commonly used to lose weight:

  • A low-fat, average-protein diet
  • A low-fat, high-protein diet
  • A high-fat, average-protein diet
  • A high-fat, high-protein diet

Protein in the diets ranged from 15% to 25% of calories, fat from 20% to 40% of calories, and carbs from 35% to 65% of calories. No specific popular diets were studied, Sacks tells WebMD, although the four resemble some popular weight loss strategies. Each of the four diets used in the new study had the same personalized calorie-reduction goals and all were low in saturated fat and cholesterol and high in dietary fiber so as to be heart-healthy.

Participants in this clinical trial, funded by the National Institutes of Health, were 30 to 70 years of age, and were either overweight or obese, with a body mass index (BMI) of 25 (the start of overweight) or higher. They recorded food intake in a diary or an online tool that kept them posted on how their intake compared with their goals. Group diet counseling sessions were scheduled at least twice a month for the study, which ran from late 2004 through the end of 2007, and one-on-one sessions were held every eight weeks.

Participants were each given a calorie goal ranging from 1,200 to 2,400 calories a day, and were asked to do moderate-intensity activity for 90 minutes a week, with brisk walking acceptable.

Participants lost similar amounts of weight -- 13 pounds on average at six months -- on each of the eating plans; they maintained a 9-pound loss, on average, at the two-year follow up mark, when 80% were still in the study.

All the diets also improved risk factors for cardiovascular disease, although there were some differences in specific results. For instance, the lowest-carb diet boosted HDL "good" cholesterol levels 9% while the higest-carb plan increased it by 6%.

Similar reports of hunger, fullness, and cravings were given by the dieters on all four eating plans.

While the 13-pound initial loss may not seem like much, Sacks says it represents 7% of the dieters' starting weight; previous studies have shown a loss of 5%-10% will help reduce heart disease risk factors and other problems.

'No Magic Diets'

"The message is people can lose a modest amount of weight and keep it off for an extended period of time," says George A. Bray, MD, a professor of medicine at the Pennington Biomedical Research Center of the Louisiana State University System in Baton Rouge, and a study co-author.

"I think the important message for people is, there are no magic diets," he says.

Next, the researchers hope to tease out whether the diet works better for obese dieters -- about 75% of the participants -- or for those who are overweight but not obese. That subgroup analysis is underway now, Bray tells WebMD. "My guess is, those who are overweight will do almost as well as the obese."

The counseling sessions and meetings were a valuable part of the program, Sacks says, and those who attended lost a bit more. "They gave people a sense of support, gave participants a chance to ask questions, meet other people, and get tips."

Sack's advice? "Find a diet that's heart-healthy. Follow it, and really be mindful of your intake. Get some support from other people in your life or from organized groups."

Finally, give it time. The best way, Sacks add, is to focus on a mild reduction in intake over the long haul.

Second Opinions

The best-diet study findings don't surprise Lona Sandon, RD, a spokeswoman for the American Dietetic Association and an assistant professor of clinical nutrition at the University of Texas Southwestern Medical Center, Dallas.

"As shown in this study, any diet will help you lose weight regardless of where the calories come from," she tells WebMD.

Ultimately, she adds, "the diet that works for weight loss is the one that is right for you." She urges dieters to approach weight loss on an individual level, taking into account their dietary needs and preferences.

Martijn Katan PhD, from the Institute of Health Sciences, VU University, Amsterdam takes a somewhat different view of the findings.

In an accompanying editorial, he notes that at the end of two years, average body mass index of participants was still in the obese range and their weight was going back up. Pointing to successful community programs in Europe, Katan argues that rather than an individual diet approach, perhaps what we really need is a change in paradigm, where groups and communities come together to encourage healthier food consumption and increased movement. "Obesity may be a problem that cannot be solved by individual persons but that requires community action," he says.

Show Sources


Frank M. Sacks, MD, professor of cardiovascular disease prevention, Harvard School of Public Health, Boston.

George A. Bray, MD, professor of medicine, Pennington Biomedical Research Center of the Louisiana State University System, Baton Rouge, La.

Sacks, F.M. The New England Journal of Medicine, Feb. 26, 2009; vol 360: pp 859-873.

Lona Sandon, RD, spokeswoman, American Dietetic Association; assistant professor of clinical nutrition, University of Texas Southwestern Medical Center, Dallas.

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