Girls who regularly ate breakfast, particularly one that includes cereal, were slimmer than those who skipped the morning meal, according to a study that tracked nearly 2,400 girls for 10 years. Girls who ate breakfast of any type had a lower average body mass index, a common obesity gauge, than those who said they didn't. The index was even lower for girls who said they ate cereal for breakfast, according to findings of the study conducted by the Maryland Medical Research Institute. The study received funding from the National Institutes of Health and cereal-maker General Mills Inc. "Not eating breakfast is the worst thing you can do, that's really the take-home message for teenage girls," said study author Bruce Barton, the Maryland institute's president and CEO. The fiber in cereal and healthier foods that normally accompany cereal, such as milk and orange juice, may account for the lower body mass index among cereal eaters, Barton said. The results were gleaned from a larger NIH survey of 2,379 girls in California, Ohio and Maryland who were tracked between ages 9 and 19. Results of the study appear in the September issue of the Journal of the American Dietetic Association. Nearly one in three adolescent girls in the United States is overweight, according to the association. The problem is particularly troubling because research shows becoming overweight as a child can lead to a lifetime struggle with obesity. As part of the survey, the girls were asked once a year what they had eaten during the previous three days. The data were adjusted to compensate for factors such as differences in physical activity among the girls and normal increases in body fat during adolescence. A girl who reported eating breakfast on all three days had, on average, a body mass index 0.7 units lower than a girl who did not eat breakfast at all. If the breakfast included cereal, the average was 1.65 units lower, the researchers found. Breakfast consumption dropped as the girls aged, the researchers found, and those who did not eat breakfast tended to eat higher fat foods later in the day. "We think it kick-starts your metabolism because you've eaten something," Barton said. "When you get to lunch you're not starving and you can make reasonable choices for lunch and dinner." John Kirwan, a professor of medicine at Case Western Reserve University's Schwartz Center for Nutrition and Metabolism, said the findings may be "more reflective of overall eating habits and quality of food consumed." "Those who eat breakfast on a regular basis are more likely to have a structured eating plan throughout the day and consequently are less likely to snack between meals and consume empty calories," said Kirwan, who has studied the effect of breakfast consumption on exercise performance and was not involved in the study. He also pointed out that the study did not distinguish between low-sugar and high-sugar cereals, noting growing evidence that those who eat so-called low glycemic foods have a lower risk of obesity, diabetes and cardiovascular disease. While cereal can often be high in fiber and low in fat, "you can't walk away saying, I'm going to eat cereal and lose weight," said Melinda Johnson, a dietitian with the Arizona state health department and an ADA spokeswoman. Johnson also noted, however, that the foods often consumed with cereal tend to be healthy, and the study was another in a series to find a link between breakfast consumption and lower body mass index. "You can walk away saying breakfast has been shown in lots of different studies to be really important for my children," Johnson said. "So parents can feel confident that serving cereal is definitely not going to do harm and eating breakfast is the right thing to do."