By Rita Rubin
WebMD Health News
Reviewed by Hansa D. Bhargava, MD
Sept. 2, 2014-- Your mother might've told you breakfast is the most important meal of the day.
Some recent reports, though, might make you think Mom's take on breakfast is about as credible as other old wives' tales.
The reports that challenge the importance of breakfast say most studies linking it to a smaller waistline and improved health have been observational. Observational studies can't prove cause and effect, though.
Skeptics wonder whether some other quality common in breakfast-eaters -- or breakfast-skippers, for that matter -- might have a greater impact on their health and weight than the meal itself. Researchers also say how the studies are done may explain the conflicting results.
Several scientists who've studied the relationship between eating breakfast and health -- all of whom said they eat breakfast daily -- helped us sort it out.
Q. If I want to lose weight, why not skip breakfast? After all, two meals have fewer calories than three.
A. The desire to lose weight is one of the most frequently cited reasons for skipping breakfast. But many observational studies have found that people who skip breakfast are more likely to be overweight. The theory is that they more than make up for the missed calories in the morning by eating more at lunch or snacking all day.
But a study published in June challenged these beliefs. The study was a randomized controlled trial, considered the gold standard of medical research. In this type of study, volunteers don't get to decide whether they eat breakfast, but are instead randomly assigned to either eat it or not.
The study showed that when people skip breakfast, "overall, there's still a similar intake or a lesser intake (of calories) over the whole day," says researcher Krista Casazza, PhD, RD.
Another small randomized trial published by Cornell University researchers in Physiology & Behavior in 2013 found that college students ate about 145 calories more at lunch when they ate nothing in the morning than they did on a day when they ate breakfast. Considering that their breakfasts averaged about 625 calories, skipping it still resulted in a savings of about 450 calories by day's end, according to the study.
Whether that calorie deficit lasts for more than a few days and leads to weight loss remains to be seen, says Harvard School of Public Health researcher Rania Mekary, PhD. "Your metabolic rate might end up decreasing," she says. "If you starve yourself, you might lose weight, but is that something good long-term?"
Researchers point out that randomized trials have shortcomings, as well. They are often small and last only a few days.
The bottom line is that while research hasn't shown eating breakfast can lead to weight loss, neither does it show that eating breakfast makes you pack on the pounds, says Heather Leidy, PhD. She's an assistant professor in the department of nutrition and exercise physiology at the University of Missouri School of Medicine.
Q. What if you don't eat anything until after you've been up for a couple of hours or more? Does that count as breakfast?
A. Does eating later in the morning count as breakfast or a snack, especially if it's something small and not a calorie-laden meal? In many studies, researchers typically ask only whether participants ate breakfast, not what they ate or when they ate it.
"There's no real standard definition of breakfast," says Megan McCrory, PhD. She's an associate professor of nutrition at the Georgia State University Byrdine F. Lewis School of Nursing and Health Professions. Some people might call that container of yogurt scarfed down at their office a morning snack, while others might call it breakfast, McCrory says, muddying the research findings. More study is needed, she said in an article published in July in Physiology & Behavior.
Mekary says she wondered whether people who said they skipped breakfast actually ate the same amount of that meal but called it snacking. She and her colleagues had asked participants in the Nurses Health Study whether they snacked before lunch as well as whether they ate breakfast. In one analysis of their data, Mekary lumped together all of the before-lunch snackers who said they didn't eat breakfast and compared them to the women who said they did. Both groups had a similarly lower risk of type 2 diabetes compared to women who said they ate nothing before lunch, in part because the morning eaters tended to weigh less. In other words, whether you call it breakfast or a snack and eat it first thing or later in the morning, the potential benefits appear to be similar, Mekary says.
Q. What is the breakfast of champions?
A. Whether grabbing a doughnut is better than no breakfast at all remains to be seen, Leidy says. "Some of our studies suggest that it is better to eat something for breakfast as opposed to skipping," she says. "On the other hand, we also show that eating a high sugar/high carbohydrate breakfast is detrimental in terms of appetite control and snacking."
A breakfast high in protein -- such as Greek yogurt with blueberries, granola, and nuts, or a breakfast burrito with eggs, lean meat or soy, and vegetables -- is a better choice, Leidy says.
Q. Can eating breakfast make me smarter?
A. It's probably too late for you, but it might work for your kids.
An observational study of Chinese kindergartners published in 2013 found that those who regularly ate breakfast had higher IQ scores than their peers who didn't. The difference remained even after accounting for other factors that can influence IQ, such as parents' education and occupations.
Casazza, although skeptical of the benefits of breakfast for adults, says "a significant amount of data" support the meal's importance for the brain in children and teens.
Mekary, who has a 3½-year-old daughter, says, "I would never send her to preschool without breakfast."
Q. Does eating breakfast each day help keep the doctor away?
A. "My findings highly suggest that breakfast is beneficial for you," Mekary says.
Besides the lower risk of type 2 diabetes in breakfast-eaters in the Nurses Health Study, reported in 2013 in the American Journal of Clinical Nutrition, she and her colleagues have published findings of a link between eating breakfast and the lower risk of other diseases. In 2013, they wrote in the journal Circulation that eating breakfast was linked with a lower risk of heart disease in the all-male Health Professionals Follow-Up Study. And in 2012, using data from the health professionals study, they reported in the American Journal of Clinical Nutrition that men who ate breakfast also had a lower risk of type 2 diabetes.
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