Low-carb diet 'most effective'
2008-07-17 14:14
Atlanta - The Atkins diet may have proved itself after all: A low-carb diet and a Mediterranean-style regimen helped people lose more weight than a traditional low-fat diet in one of the longest and largest studies to compare the duelling weight-loss techniques.
A bigger surprise: The low-carb diet improved cholesterol more than the other two. Some critics had predicted the opposite.
"It is a vindication," said Abby Bloch of the Dr Robert C and Veronica Atkins Foundation, a philanthropy group that honours the Atkins' diet's creator and was the study's main funder.
The research was done in a controlled environment - an isolated nuclear research facility in Israel. The 322 participants got their main meal of the day, lunch, at a central cafeteria.
"The workers can't just go out to lunch at a nearby Subway or McDonald's," said Dr Meir Stampfer, the study's senior author and a professor of epidemiology and nutrition at the Harvard School of Public Health.
Calories
In the cafeteria, the appropriate foods for each diet were identified with coloured dots, using red for low-fat, green for Mediterranean and blue for low-carb.
As for breakfast and dinner, the dieters were counselled on how to stick to their eating plans and were asked to fill out questionnaires on what they ate, Stampfer said.
The low-fat diet - no more than 30% of calories from fat - restricted calories and cholesterol and focused on low-fat grains, vegetables and fruits as options. The Mediterranean diet had similar calorie, fat and cholesterol restrictions, emphasising poultry, fish, olive oil and nuts.
The low-carb diet set limits for carbohydrates, but none for calories or fat. It urged dieters to choose vegetarian sources of fat and protein.
"So not a lot of butter and eggs and cream," said Madelyn Fernstrom, a University of Pittsburgh Medical Centre weight management expert who reviewed the study, but was not involved in it.
Most of the participants were men; all men and women in the study got roughly equal amounts of exercise, the study's authors said.
Cholesterol
Average weight loss for those in the low-carb group was about 4.7kg after two years. Those in the Mediterranean diet lost 4.5kg, and those on the low-fat regimen dropped 3kg.
More surprising were the measures of cholesterol. Critics have long acknowledged that an Atkins-style diet could help people lose weight, but feared that over the long term, it may drive up cholesterol because it allows more fat.
But the low-carb approach seemed to trigger the most improvement in several cholesterol measures, including the ratio of total cholesterol to HDL, the "good" cholesterol.
Doctors see that ratio as a sign of a patient's risk for hardening of the arteries. "You want that low," Stampfer said.
The ratio declined by 20% in people on the low-carb diet, compared to 16% in those on the Mediterranean and 12% in low-fat dieters.
- AP