Safety of Atkins Diet Questioned

COPENHAGEN, Denmark--The trendy Atkins diet may not be ideal due to a multitude of reported side effects, increased risk of second-line eventual cardiovascular disease and cancer, and lack of long-term clinical trials, according to a review published in the September issue of The Lancet (364, 9437:897-99, 2004) (www.thelancet.com).

According to Arne Astrup, Ph.D., the author of the review, the carbohydrate restriction of the Atkins diet may produce weight loss through ketosis and excretion of water, while the high protein intake and limited food choices of the diet may create satiety and help curb energy intake, respectively. Paradoxically, these factors allow low carb dieters to eat a high fat, high protein diet ad libitum yet lose weight, at least over the short term. Further, Astrup stated clinical evidence has shown weight loss on an Atkins-type diet is primarily attributable to depletion of fat stores rather than lean body mass or water excretion, which is normally supported by beneficial changes in cardiovascular risk factors.

However, Astrup questioned the safety of the diet since adherents have reported side effects including halitosis, muscle cramps, diarrhea, general weakness and rashes. Further, the long-term effects of the diet on disease prevention are unknown, and the mechanisms by which the diet produces weight loss require clarification, Astrup added.

Restricted intake of carbohydrate-rich foods including fruits, vegetables and grains may lead to long-term nutritional inadequacy and second-line increased risk of cardiovascular disease and cancer, said Astrup, who is also a medical adviser for Weight Watchers, Denmark.

However, Ronkonkoma, N.Y.-based Atkins Nutritionals Inc. begs to differ.

All of the studies to date--and there are currently 36 studies that look at cardiovascular risk factors for up to one year--show improvements in cardiovascular risk factors, said Colette Heimowitz, vice president of education and research with Atkins Nutritionals Inc. Astrups comments are assumptions and we need to go by what the science has demonstrated, not by what someone assumes will happen. And, after one year, those following the Atkins diet can begin to integrate a lot more vegetables and fruits into the plan.

Astrup called for further research to clarify the mechanisms by which the Atkins diet produces weight loss and long-term studies to assess the diets effects on nutritional status, body composition, and fasting and postprandial cardiovascular risk factors as well as adverse effects.

There is an urgent need for longer and larger studies in obese and moderately overweight individuals to assess weight-loss efficacy, with careful assessment of energy balance and cardiovascular and diabetes risk factors, constipation, markers of kidney and bone health, nutritional adequacy, dietary compliance and quality of life, Astrup said. Without such studies, Astrup concluded, low carbohydrate diets cannot be recommended.

One year is the longest any dietary program has been studied to date, Heimowitz said. There are no studies longer than one year on any program--including low fat. NIH [the National Institutes of Health] is currently doing a three-year study [on low carb dieting]. Im sure the study will reflect the long-term effects Dr. Atkins observed in his clinical practice for 30 years. But scientists need to find it out for themselves.