WASHINGTON — A new study from the Economic Research Service (E.R.S.) of the U.S. Department of Agriculture has found that many school policies and practices are associated with the fat content of meals they serve through the National School Lunch Program. The study, "Meeting Total Fat Requirements for School Lunches," comes on the heels of an earlier U.S.D.A. report that found that while most schools met requirements for vitamins, protein, calcium, and iron, only one in five schools served lunches that met the U.S.D.A. standard for total fat.

"A number of recent studies indicate that one-third of all children between the ages of 6 and 19 are overweight or obese and we must take immediate steps to improve the nutritional quality of school meals and the health of the school environment," said Secretary of Agriculture Tom Vilsack. "We have a window of opportunity to make progress on improving the nutrition of school lunches as Congress reauthorizes the Child Nutrition Act, but I also urge schools across the country to embrace the policies and practices identified in this study to help reduce the fat content of school meals and help our children to lead healthier lives."

The study used data from the School Nutrition Dietary Assessment-III to calculate the effect of policies and characteristics on the fat content of National School Lunch Program lunches served by 397 schools during the spring of 2005. Sixty-three per cent of the schools in the sample were elementary schools and 37% were middle schools and high schools combined.

Schools were divided into three categories based on the average fat content in school lunches, including: 1) no more than 30% of calories from fat; 2) 30% to 35% of calories from fat; or 3) more than 35% of calories from fat.

According to the study, the school policies and practices most often linked to lower fat content were promotion of fresh fruits and vegetables or locally grown foods, offering low-fat dairy products, eliminating vending machines in middle and high schools, and adopting a "nutrient content" or "enhanced food-based" meal planning method where lunches are planned according to the nutrient content of food items.

Higher fat content in school lunches was linked to policies and practices offering french fries and desserts, availability of a la carte foods in elementary schools and "traditional" meal planning, which must include certain types of food such as meat, vegetable, starch, etc.

The study also found that elementary schools were more likely to comply with fat requirements than were middle and high schools. Twenty-six per cent of elementary schools served lunches that met the fat requirement, 43% served lunches in the middle category, and 31% served lunches in the highest fat content category. This compared with middle schools and high schools, where 12% served lunches with the lowest fat content, 36% in the middle category and 52% in the highest fat content category.

The E.R.S. noted that the results are consistent with other research showing older students face a less healthy school food environment.

"Our findings show that the average fat content of lunches served in schools does differ across various school policies and characteristics," the E.R.S. said. "The presence of a la carte foods and vending machines seems to indirectly affect the fat content of U.S.D.A. lunches, though there was no evidence of a relationship between lunch fat content and other competitive food policies such as pouring rights, food and beverage restrictions, and other sources of snacks.

"Nutrition and food-purchasing policies — such as wellness policies, nutrition and health councils, and nutrition education — did not correlate with the fat content in school lunches. Many lunch planning characteristics — such as menu planning method; the offering of french fries, desserts or fruits/vegetables; and offering only low-fat milk — were significant, especially for high schools."