Eating a low-carb diet results in greater weight loss and greater improvements in blood cholesterol than a traditional low-fat diet or a Mediterranean diet, say nutrition researchers from the Harvard School of Public Health.
In this new study, 322 people were assigned to a low-fat diet, a Mediterranean diet or a low-carb diet. For two years, they were given a lunch that corresponded to their assigned diet in the controlled environment of a research facility cafeteria.
The low-fat diet contained no more than 30 percent of calories from fat with an emphasis on whole grains, vegetables and fruits.
The Mediterranean diet was similar to the low-fat diet in terms of calorie, fat and cholesterol restrictions - but emphasized poultry, fish, olive oil and nuts. The low-carb diet set limits for carbohydrates, but set no limits on calories or fat.
For breakfast and dinner, the study participants received nutrition counselling to help them follow their assigned diets.
After two years, the average weight loss for people on the low-carb diet was 10.3 pounds. People who ate according to the Mediterranean diet lost 10 pounds, and those who followed the low-fat diet dropped 6.5 pounds.
The low-carb diet resulted in the greatest improvement in the ratio of total cholesterol to "good" HDL cholesterol. This ratio declined by 20 percent in people on the low-carb diet, compared to 16 percent in those on the Mediterranean diet and 12 percent in the low-fat dieters.
Previous research has supported the effectiveness of the low-carb diet in producing short-term weight loss in men. This is the first long-term study to show that it is more effective than the low-fat diet and the Mediterranean diet for improving blood cholesterol levels.
High blood cholesterol is a risk factor for heart disease that can be managed by eating a diet that is low in saturated and trans fats and high in foods that contain soluble fibre - like apples and oats.
This study was published in the July 17, 2008 issue of The New England Journal of Medicine.
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