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Low-Carbohydrate Ketogenic Diet Associated with Greater Weight Loss, Better Lipid Profile than Low-Fat Diet: Presented at AHA

By Peggy Peck

CHICAGO, IL -- November 19, 2002 -- Obese patients who followed a high-fat, low-carbohydrate "Atkins diet" for six months lost more weight and experienced more significant favourable changes in lipid profiles than did those who tried a low-fat diet for six months, according to one study.

This finding was presented at the American Heart Association's 2002 Scientific Sessions by Dr. Eric Westman, assistant professor of medicine, Duke University, Durham, North Carolina, United States.

Dr. Westman said he was prompted to the diet after treating several patients who were "losing significant weight using the Atkins diet." The Robert C. Atkins Foundation of New York funded Dr. Westman's study, but Dr. Westman said that in his clinical practice he does not recommend the Atkins' diet.

Dr. Westman said did not expect the high fat regimen to do better than "the standard low-fat, high-carbohydrate diet that we use at the Duke Diet Center."

Nonetheless, he said that carbohydrate-induced hypertriglyceridemia might contribute to the increasing prevalence of the metabolic syndrome, which consists of abdominal obesity, high triglycerides, low high-density lipoprotein (HDL)-cholesterol, high blood pressure, and high fasting serum glucose. Thus, he said that a well-designed study of the effects of a low-carbohydrate ketogenic diet program on body weight and serum lipids was warranted.

Dr. Westman randomized 120 volunteers who were overweight (80 percent Caucasians, 75 percent females) to a low-carbohydrate ketogenic diet (LC) (less than 20 gm/day, "Atkins-type") plus nutritional supplements (including fish, borage, and flaxseed oil) or to a low-fat, low-calorie diet (LF).

All volunteers were overweight or obese and hyperlipidemic (low-density liprprotein [LDL] greater than 130mg/dL or triglycerides greater than 200mg/dL) but were otherwise healthy. The subjects attended group meetings biweekly for three months, then monthly. Outcomes were body mass index (BMI) and serum lipids using a nuclear magnetic resonance lipoprotein subclass technique.

The mean age of subjects was 46 years; the mean baseline body mass index (BMI) was 34.5 kg/m². The weight loss over six months was 13.8 percent for LC (n=36) and 8.8 percent for LF (n=27).

The reduction in very low-density lipoprotein (VLDL) was greater for LC than LF (-49 percent versus -17 percent, p<0.01). Both groups had a 73 percent reduction in small LDL, an increase in LDL diameter (+5 percent for LC, +1 percent for LF), and a decrease in LDL particle concentration (-7 percent for LC, -16 percent for LF). The increase in large LDL was greater for LC (+53 percent) than LF (+2 percent), p < 0.01.)

The LF group had a 1 percent decrease in HDL, and the LC group had an 8 percent increase in HDL levels. The reduction in TG/HDL ratio was greater for LC than LF (-53 percent vs. -6 percent, p<0.01).

Dr. Westman said he thinks the Atkins diet "works" because people stay on it and lose more weight. Weight, he says, appears to be the real key to reducing heart disease risk factors.

Dr. Alice Lichtenstein, professor of family medicine and community health at Tufts University, Boston, Massachusetts, and a member of the AHA's nutrition committee, said she still has real doubts about the value of the Atkins diet.

"If this really worked, we have at least a dent in the obesity epidemic. Everyone would be on it," said Dr. Lichtenstein, who added that a "calorie is a calorie and losing weight is all about calories." She says that people who lose weight on the Atkins diet simply take in fewer calories. Moreover, she said that the favorable lipid changes are likely to have more to do with the "supplements, especially fish oil" than with the diet.

Dr. Lichtenstein said that the AHA dropped its support of a low-fat diet a few years ago and now supports a well-balanced diet that includes a lot of fruits, vegetables, whole grains, and at least two servings a week of fish-fatty fish. But "it isn't just diet. We promote a healthy lifestyle that means a good well balanced diet, exercise and no smoking."

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