London Dieters on the popular high-fat, low-carb Atkins approach lose just as much body fat as those on low-fat diets, but the annoying low-carb side effects could mean problems down the road, according to a scientist who reviewed five dozen diet studies.
Danish obesity expert Dr. Arne Astrup, whose survey is published this week in The Lancet medical journal, concludes that headaches, muscle weakness and either diarrhea or constipation are reported more often by Atkins dieters than people on conventional diets. Those side effects may be signs that the eating plan isn't healthy in the long run, he says.
However, other experts said the diet remained a viable option for some because the side effects weren't bad enough to throw them off the eating plan famous for its shunning of bread, pasta and many fruits.
"More people stayed in the low-carb group than in the low-fat group, so you've got to wonder how severe those side effects were if more people kept to the low-carb diet," said William Yancy, a Duke University researcher who conducted one of the major studies that Astrup reviewed.
The Atkins diet, which allows unlimited consumption of protein and fat but drastically limits carbohydrates and does not restrict calories, has had a following for decades but only recently has come under serious scientific scrutiny. It has been embraced by an estimated 20 million people.
In his review, Astrup, director of research in the department of human nutrition at the Royal Veterinary and Agricultural University in Frederiksberg, Denmark, examined the evidence from about 60 studies on the Atkins and other low-carb diets.
Several small studies in the past year or two have surprised the experts by showing that people lose more weight on the Atkins diet than on the standard low-calorie, low-fat diet, at least in the short term, with even better cholesterol improvements.
Longer studies have since shown that when dieters are followed for a year, the total weight loss ends up almost the same with the two approaches. The long-term effect on cholesterol has not been studied yet.
The most frequent complaints with low-carb diets are constipation and headache, which are readily explained by the lack of fruit, vegetables and whole grains, Astrup said.
Also, bad breath, muscle cramps, diarrhea, general weakness and rashes are more often reported on low-carb diets than on low-fat diets, Astrup found.
"The majority had some of these side effects in the Atkins group. In the control group, almost nothing," he said.