We’ve been told for ages that breakfast is the most important meal of the day, and that skipping it puts us at greater risk of not being able to maintain a healthy weight.

That recommendation — codified in many dietary guidelines — is based on the presumption that having a hearty breakfast helps to discourage us from filling up on extra calories later in the day.

But a new study — a major review of more than a dozen randomized controlled trials on the subject — calls that presumption into serious doubt. It found that skipping breakfast has essentially no effect on our weight.

If anything, people who eat breakfast tend to down more calories during the day than those who skip that meal, the study concluded.

“While breakfast has been advocated as the most important meal of the day in the media since 1917, there is a paucity of evidence to support breakfast consumption as a strategy to achieve weight loss, including in adults with overweight or obesity,” the study’s authors write.

“This systematic review of randomized controlled trials examining weight change in adults consuming or skipping breakfast found no evidence to support the notion that breakfast consumption promotes weight loss or that skipping breakfast leads to weight gain,” they add.

How the belief took hold

Support for the importance of breakfast is based primarily on findings from a series of observational studies that have shown people who are obese tend to skip breakfast. But observational studies can demonstrate only a correlation between two things, not a cause-and-effect relationship.  Other factors, ones not directly accounted for in those studies, may explain their results.

Indeed, research has also shown that people who skip breakfast tend to be, on average, poorer, less healthy and less likely to have a healthy diet than those who eat a morning meal. Those factors are also associated with obesity.

The authors of the current study, which was published this week in The BMJ, wanted to see what the best evidence — randomized controlled trials — said about breakfast. They evaluated data from 13 trials on the topic that met their inclusion criteria, including seven that looked at the effect of eating breakfast on weight change and 10 that looked at its effect on energy (calorie) intake.

All the studies randomly assigned participants to one of two groups: breakfast consumption or no breakfast consumption (skipping breakfast). Most of the studies took place in the United Kingdom or in the United States.

Key findings

The researchers pooled the data from the 13 studies and then conducted a meta-analysis. Despite some inconsistencies among the studies, they found a very small difference in weight between those who skipped breakfast and those who didn’t.

The people who skipped breakfast weighed, on average, about one pound lighter.

The analysis also revealed that the breakfast-eaters in the studies consumed an average of 260 more calories per day than the breakfast-skippers.

How much the participants weighed when they entered the clinical trial didn’t make any significant difference to the results. Nor did it matter which country they lived in.

“Although eating breakfast regularly could have other important effects, such as improved concentration and attentiveness levels in childhood, caution is needed when recommending breakfast for weight loss in adults, as it could have the opposite effect,” the study’s authors conclude.

An individual preference

The meta-analysis comes with its own limitations. Most notably, the clinical trials it analyzed varied widely in quality and in the length of time they followed their participants.

Still, as Dr. Tim Specter, a professor of genetic epidemiology at King’s College London (and self-proclaimed breakfast-lover), points out in an accompanying commentary, the “disadvantages of skipping breakfast have now been debunked by several randomized trials.”

He notes that previous scientific reviews have come to the same conclusion.

No one, however, should take these findings to mean that they should suddenly stop eating breakfast, he adds. There is no “one size fits all” approach to breakfast.

“Some people are programmed to prefer eating food earlier in the day and others later, which might suit our unique personal metabolism,” he writes.

So go ahead and skip the morning oatmeal or eggs, toast and jam, if you feel like doing so.

“While waiting for guidelines to change,” says Specter, “no harm can be done in trying out your own personal experiments in skipping breakfast.”

FMI:  You’ll find the study and the commentary on the BMJ’s website.