Breakfast is food for the brain and for the rest of your body. And taking in those morning calories are worth it, even for people who are worried about their weight, a new study finds. 

The study was led by Marlene Schwartz, a psychologist who studies obesity(肥胖). Her group studied 600 middle-school students. Over three years, students from 12 different schools were asked about their breakfasts. Throughout the study about 34% to 44% of all students said they regularly ate breakfast at home. Up to 17%, or almost one in every six kids, regularly ate breakfast at school. Overall, about one in every 10 kids reported eating breakfasts both at home and at school. Also their eating habits became different somewhat as the kids got older. For example, fifth graders were more likely to regularly eat breakfast at home. But by seventh grade, 22% of the kids often skipped breakfast.

Surprisingly, at every age, kids who ate breakfast were less likely to be overweight. This was true even for those who ate breakfast at home and at school. It also found that the students who skipped breakfast most often were those most likely to be overweight. These findings may seem puzzling. Yet Schwartz and her workmates can think of several possible explanations.

Skipping breakfast may make people too hungry later in the day, she says. Then someone may eat more food than their body needs, says Schwartz. What’s more, not eating in the morning upsets something in the body that keeps our brains and bodies working well. And also it’s difficult for children to pay attention in class if they arrive without having breakfast. 

But why should eating two breakfasts not lead to weight gain? One explanation may be that school breakfasts are very healthy and controlled in size, notes Schwartz. What’s more, most of the double-breakfast eaters are boys. These kids move around a lot, and this can make them not gain weight.