Scientists have found that people whose diets are highest in carbohydrates actually eat fewer calories per day and are less likely to be obese than people who eat diets with higher levels of fat and protein.

Researchers at the Agricultural Research Service (ARS), the USDA's chief scientific research agency, studied data analysis of carbohydrate intakes from the USDA's Continuing Survey of Food Intakes by Individuals for the years 1994-1996.

The analysis, which is published in the June 2002 issue of the Journal of the American College of Nutrition, showed that persons whose diets were highest in carbohydrates not only consumed 200 to 300 fewer calories per day, but also had diets higher in nutrients. The study's results are contrary to some "fad diets" that emphasise decreasing carbohydrate intakes while increasing protein and fat.

In the study, scientists divided a nationwide pool of 10,014 people into four carbohydrate-intake dietary patterns, from lowest to highest. People eating the high-carbohydrate diet got 55% or more of their calories from carbohydrates; in the lowest carbohydrate diet, people consumed 30% or less of their calories from carbohydrates.

People eating the high-carbohydrate diet were also more likely to meet the federal government's Dietary Guidelines for Americans' recommendations for both total fat (no more than 30%) and saturated fat (no more than 10%).

The high-carbohydrate group had to eat more food to get 1,000 calories than those in the low-carbohydrate group because of the choices they made, according to nutritionist and lead author Shanthy A. Bowman of ARS' Community Nutrition Research Group, Beltsville, Md.

Those in the high-carbohydrate diet had the highest fruit and fibre intake, and they made low-fat choices from milk, meat, poultry and fish products. They also had the lowest average body-mass index (BMI), which indicates the percentage of fat in the body. As a major health-risk factor, obesity has increased considerably during the past 20 years.