Why Do High-Protein Diets Work?

Lose more weight when you eat lean, red meat

From the WebMD Archives

May 9, 2003 ­ Carnivores, rejoice! Red meat might be key to your high-protein diet. That's the finding from a new study, presented at an annual meeting of the American Heart Association.

"This is notthe Atkins diet," says lead investigator Manny Noakes, PhD, a research dietitian with the Commonwealth Scientific Industrial Research Organization in Adelaide, Australia. "This is a high-protein diet, but it includes more fruits and vegetables than Atkins," she tells WebMD.

The Atkins diet, which has drawn criticism from dietitians, is a high-protein diet but allows few carbohydrates (at least in the first few weeks). Later, dieters are allowed to gradually add in limited amounts of fruits and vegetables. Atkins allows too much saturated fat and is too skimpy on fruits and vegetables, many dietitians say, but research has shown that people on the Atkins diet do lose weight without upping their cholesterol.

In their study, Noakes and colleagues set out to analyze red meat's effects -- very lean red meat, that is -- on risk factors for heart disease and diabetes, she explains. However, the results turned up a surprising conclusion.

But first the data: 100 women were enrolled in the study -- all overweight, with an average body mass index (BMI) of 33. For 12 weeks, half the women ate a high-protein diet of 34% protein, 46% carbohydrate, and 20% fat. The other half ate a high-carbohydrate diet that was 17% protein, 63% carbohydrate, and 20% fat. Each diet consisted of about 1,340 calories, and protein in both diets was from lean red meat.

Who Lost More Weight?

After 12 weeks, both groups lost weight -- but some of the high-protein-diet women lost substantially more weight. Those women who had triglyceride levels higher than 133 mg/dL -- a fat in the blood -- at the study's beginning lost 25% more weight, reports Noakes. At the study's end, the high-meat eaters also had 22% lower levels of triglycerides, she says. High triglyceride levels are often seen in people at risk for diabetes.

Other measures of health -- "good" HDL and "bad" LDL cholesterol, blood sugar, and fasting insulin levels -- fell in both groups.


"You can lose weight in lots of different ways," Noakes says. "But certain people might do better on a certain dietary pattern with less carbohydrates, more protein. They will feel less hungry, be able to tolerate eating less for longer periods of time. We find that's generally true of high-protein diets."

Whether or not you have high triglyceride levels in your blood, this type of red meat, high-protein diet might work for you, she adds. "It's whether or not a particular pattern suits you. A high-carbohydrate diet -- rice, pasta, fruit, vegetables -- hasn't always worked for people. There are lots of strategies to lose weight, and this is one of them."

"Younger women may be especially interested in the high-protein diet, since it has lots of calcium and iron, and provides lots of micronutrients," Noakes adds. "We believe that a higher-protein pattern is more nutrient rich and may in fact be a diet of choice for women who are trying to lose weight."

Noakes' high-protein diet is certainly healthy, says Kathleen Zelman, RD, spokeswoman for the American Dietetic Association (ADA). In fact, the carbohydrates, protein, and fats in both diets that Noakes tested are within approved ranges set by the ADA and the National Academy of Sciences, she tells WebMD.

"We're not talking Atkins," says Zelman. "These are within normal limits."

Other studies have documented the effectiveness of increasing protein, she tells WebMD. Protein works partly because it makes us feel full. Also, studies have shown that high protein and fewer carbohydrates work well together in terms of weight loss.

Bottom line: Eat fewer refined carbohydrates -- table sugar, baked goods, white bread, pasta -- and more fruits and vegetables, says Zelman. Eat lots of lean protein -- sirloin steak, flank steak, chicken, eggs, tofu, and fish.

WebMD Weight Loss Clinic - Medical News Reviewed by Michael W. Smith, MD on May 09, 2003


SOURCES: American Heart Association's 4th Annual Conference on Arteriosclerosis, Thrombosis and Vascular Biology, Washington, D.C., May 8-10, 2003. Manny Noakes, PhD, research dietitian, Commonwealth Scientific Industrial Research Organization, Adelaide, Australia. Kathleen Zelman, RD, spokeswoman, American Dietetic Association. WebMD Medical News: "Skeptics Think Twice About Atkins Diet."

© 2007 WebMD, Inc. All rights reserved.


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