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Medical Studies Offer Support for Low-carbohydrate Diets
Obesity Doubles Risk Of BlindnessLONDON (Reuters) - Britain's increasing number of obese adults and children face twice the risk of losing their sight from a range of ..... OB GYN News; 1/1/2005; McNamara, Damian
ORLANDO, FLA. -- Low-carbohydrate ketogenic diets promote greater weight loss and improve certain serum lipids, compared with low-calorie diets, according to a literature review.
Low-carbohydrate strategies for weight loss, such as the Atkins or South Beach diets, are very popular despite a relative scarcity of scientific data to support their use. Since 2003, six published randomized, controlled trials have compared these diets with more traditional low-calorie approaches for weight control.
Researchers followed outpatients for 3 months to 1 year and compared baseline weight and serum lipids with follow-up values. All participants received recommendations for low-fat intake and regular exercise and attended group meetings.
"There was greater weight loss with the low-carb diet in all these trials," Eric C. Westman, M.D., said at a symposium on obesity sponsored by the American Society of Bariatric Physicians.
In five of these trials--which comprised from 30 to 132 participants--the average weight loss in low-carbohydrate diet groups ranged from 5.1 kg to 12 kg compared with an average weight loss of 1.9-6.5 kg in the low-calorie diet groups.
Differences were less pronounced in the sixth, most recent trial (Ann. Intern. Med. 2004;140:769-77). It may have been because the low-carbohydrate group received nutritional supplements according to the Atkins diet protocol, said Dr. Westman of the department of medicine, Duke University Medical Center in Durham, N.C.
Dr. Westman and his colleagues enrolled 119 overweight, hyperlipidemic volunteers. After 24 weeks, participants had an average 7-kg weight loss on a low-carbohydrate diet versus 6.8 kg on a low-fat, low-cholesterol, reduced-calorie protocol. Dr. Westman's research was supported by an unrestricted grant from the Dr. Robert C. Atkins Foundation.
"Both sides lost weight, so I'm not here to say there is only one way to go about this," Dr. Westman said. "It is unlikely that one diet is optimal for all overweight people.
"My patients read the Atkins book," Dr. Westman said. "I was initially suspicious and suspected patients' cholesterol would be higher, but it wasn't."
The investigators compared serum lipids of the 59 volunteers on a low-carbohydrate diet and 60 on low-calorie diets. The low-carbohydrate group had a 49% reduction in triglycerides (from 167 mg/dL to 86 mg/dL), compared with a 15% reduction for the group on a low-calorie diet (from 191 mg/dL to 163 mg/dL). In addition, the low-carbohydrate group had an 11% increase in high-density lipoprotein cholesterol level (from 54 mg/dL to 60 mg/dL), compared with a 3% decrease in the low-calorie group (from 54 g/dL to 52.5 mg/dL).
"This is pretty intriguing if concerns about cholesterol increases are a reason for not prescribing the diet," Dr. Westman said. "It has to be individualized, but indications are that cholesterol is more favorable on the low-carbohydrate ketogenic diet."
In contrast, total cholesterol levels were better in the low-fat reduced-calorie group. The low-carbohydrate group had a 4% drop (from 245 mg/dL to 236 mg/dL), compared with a nearly 6% decrease (from 240 mg/dL to 226 mg/dL) in the low-calorie group. Similarly, the low-carbohydrate group had a 1% increase in low-density lipoprotein cholesterol (from 157.3 mg/dL to 158.4 mg/dL) versus a 5% decrease (from 148 mg/dL to almost 141 mg/dL) among the low-fat reduced-calorie group.
Regarding the five earlier randomized trials, Dr. Westman said, "The cholesterol effects were present in all studies except those low in sample size."
The five studies were J. Pediatr.
2003;142:253-8; J. Clin. Endocrinol. Metab.
2003;88:1617-23; N. Engl. J. Med.
2003;348:2074-81; Ann. Intern. Med.
2004;140:778-85; and N. Engl. J. Med
By Damian McNamara
COPYRIGHT 2005 International Medical News Group
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