Plenty of research has found that eating breakfast is important for weight maintenance, metabolism and overall good health. Now, the evidence gets even stronger: a small new randomized controlled trial finds that regularly eating a substantial morning meal directly affects how fat cells function in the body by changing the activity of genes involved in fat metabolism and insulin resistance. The findings suggest that eating breakfast every morning may help lower people’s risk for type 2 diabetes and cardiovascular disease, the study authors say—and that even if a morning meal increases a person’s total calorie consumption, those calories may be offset by other energy-burning benefits.
In the study, published in the Journal of Physiology, researchers asked 49 people ages 21 to 60 to either eat breakfast or fast until mid-day, every day for six weeks. Those in the breakfast group were asked to eat at least 700 calories by 11 a.m., and at least half of those calories within two hours of waking. They could choose the foods they wanted, but most people opted for typical breakfast foods like cereals, toast and juice.
Before and after the study, the researchers measured everyone’s metabolism, body composition and cardiovascular and metabolic health. They also took biopsies of their fat cells to measure the activity of 44 different genes and proteins related to metabolism and other physiological processes, as well as the cells’ ability to take up sugar, which is the body’s response to changing insulin levels.
They found that in people who had normal weights, eating breakfast decreased the activity of genes involved in fat burning. In other words, there was some evidence that skipping breakfast actually increased fat burning, says lead author Javier Gonzalez, associate professor in nutrition and metabolism at the University of Bath in the UK, in an email. But total energy balance—the most important aspect for weight loss or weight maintenance—did not drastically differ between groups. “Breakfast consumption increased total calorie intake in lean people, but this was offset by breakfast also stimulating physical activity energy expenditure in lean people,” he says.
More importantly, eating breakfast also decreased the activity of genes involved in insulin resistance and increased the amount of sugar the cells took up—which could potentially protect against diabetes and other chronic illnesses over time. This finding is “in line with our previous observations that breakfast consumption is associated with better glucose control in fat cells,” Gonzalez says. “This may have implications for disease risk, but we need to work more on this.”
However, that’s not what they found in people with obesity. The more body fat a person had, the less their fat cells responded to insulin. At least one gene associated with fat burning was also more active among people with obesity in the group that ate breakfast, compared to the fasting group.
Fasting, meanwhile, seemed to increase the activity of genes associated with inflammation—but only in people with obesity. “Therefore, the guidelines for breakfast consumption should perhaps differ depending on whether people are lean or obese,” says Gonzalez. More research is needed, he adds, before such recommendations can be made.
Because the people in the study ate breakfasts high in carbohydrates, the researchers are unable to say whether other types of breakfasts—like high-protein meals—would have the same effects. “However, we are now exploring how different types of breakfast influence health,” Gonzalez says, “and how breakfast interacts with other health behaviors such as exercise.”
By better understanding how fat responds to food at different times of day, Gonzalez says, scientists may be able to target those mechanisms more precisely. “We may be able to uncover new ways to prevent the negative consequences of having a large amount of body fat,” he says, potentially by doing something as simple as eating breakfast on a daily basis.
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