Many parents hate to see their children skip breakfast before sending them off in the morning. Reason tells them that in order to maximize learning in school, children's bodies need plenty of fuel. A British study published in 2007 showed that parents' intuition may be correct: Well-fed children make more progress in school than children who leave home with their stomachs empty.
Children are more vulnerable than adults to missing a meal. The brain of a child is not just a scaled down version of an adult brain. It is larger in proportion to his or her body. Though the brain makes up only one-fiftieth of a child's body mass, it uses about half of the body's stores of energy. It is also changing rapidly: Nerve cells are growing and cell connections are adjusting rapidly in response to the environment. All of this increases the brain's demand for energy.
Our understanding of food intake and mental ability comes from studies of the effect of starvation. Severe food deprivation is a huge problem for intellectual growth. But these studies don't tell us much about the impact of missing a single meal. And we tend to worry more about the consequences of obesity in the United States. So we may consider a missed meal here and there a good thing.
The question for concerned parents then is, does skipping breakfast affect the learning of children who otherwise have access to plenty of food?
The researchers in the United Kingdom tried to answer the question by studying school children who were about nine years old. They designed a study to see if the size of the students' breakfast affected their ability to do their work.
After arriving at school, the children reported what they had eaten for breakfast. The scientists then grouped the children according to the size of their breakfast: small (under 150 calories), medium (150 – 230 calories) or large (over 230 calories). Over each of the four days of the study, the researchers gave half of the children a late-morning snack consisting of a 225-calorie breakfast bar. They varied how they gave out the snacks so that every child received the snack on half of the study days. This allowed them to compare the children's performances with and without the snack.
The researchers observed the children for an hour after the snack. They recorded whether the children were attending to their work or not. Children who were engaged in their work or listening to the teacher were classified as on task. Those who appeared distracted, were walking around or disrupting the class were considered to not be on task.
The children who ate the smallest breakfast were more on task on the days they got a snack than on the days they didn't. The snack made no difference for children who ate more than 150 calories for breakfast.
The brain is so important that it serves itself first. That is, the brain takes what it needs to function before any other part of the body gets fed. Even as "selfish" as the brain may be, this study demonstrates that brain function can fall off somewhat even when just one meal is missed.
The breakfast gap is a peculiar problem in the United States, where food — and images of food — are everywhere. When children eat too little in the morning their schoolwork can suffer. Eating too much after school, however, increases the risk of becoming overweight.
This study reinforces the sage advice that children should eat balanced meals with sensible portions at the right times during the day. In fact, there is some evidence that the risk of obesity can be reduced by making sure kids have a classic "wholesome" breakfast that is shorter on sugared cereals and longer on milk, fruit, eggs and whole grains.
If it seems like too tall an order, the study does provide some advice that is relatively simple to follow: At the very least, a granola bar is better than nothing at all.
Benton D, Jarvis M. "The role of breakfast and a mid-morning snack on the ability of children to concentrate at school." Physiol Behav. Feb 28, 2007;90(2-3):382-385.
Michael Craig Miller, M.D. is Editor in Chief of the Harvard Mental Health Letter. He is also associate physician at Beth Israel Deaconess Medical Center and assistant professor at Harvard Medical School. He has been practicing psychiatry for more than 25 years and teaches in the Harvard Longwood Psychiatry Residency Program.