Some news stories sugarcoat limitations of study linking skipping breakfast to heart disease

Jill Adams is an associate editor with She tweets as @juadams.

A raft of news stories this week covered yet another study that links skipping breakfast to health woes.

The study was observational and offered up this association: People who ate less than 5 percent of their total daily calories at breakfast, based on their answers on a questionnaire about their eating habits, were more likely to show signs of early atherosclerosis. Atherosclerosis is a buildup of fats, cholesterol and other substances in artery walls that can restrict blood flow.

What is breakfast?

Some outlets used appropriate language in their headlines:

Skipping Breakfast May Be Bad For The Heart — But There Are Caveats (Forbes)

Others took license and turned the finding into a recommendation for their readers:

The Surprising Reason You Should Stop Skipping Breakfast (Time)

How a Healthy Breakfast Could Curb Heart Trouble (Consumer Reports)

And yet, none of the articles we looked at asked a question that nutrition experts say is key: What did the participants eat?

“The biggest bee in my bonnet: There is no such thing as breakfast,” says Yoni Freedhoff, MD, a nutrition and weight management expert at the University of Ottawa and a contributor. When researchers (and journalists) use the word, he says, “They’re saying a bowl of Froot Loops is the same as a summer vegetable omelet. Both might be 400 calories of breakfast, but they make the conclusions totally meaningless.”

In addition, Freedhoff says, “The researchers were not controlling for what people were eating.”  

In other words, if you want to accurately assess whether skipping the morning meal is linked to a health outcome, you would want everyone in the study to eat a similar diet, or be matched up by how similar their diets were. As much as possible, you would try to isolate the skipped meal as the only condition that varies among study groups.

So the study quality leaves plenty to be desired, but it still earned news coverage.

“This message about breakfast seems to get covered from one angle,” says Allison Dostal Webster, PhD, a dietitian and nutrition researcher at the University of Minnesota and a contributor. The angle — eating breakfast is good for you — seems irresistible to news outlets seeking wellness topics. “It’s frustrating to me because I know it’s not the whole story.” 

Just an association, after all

To their credit, most news outlets pointed out that this was an association study and couldn’t prove cause and effect. For more on why this matters, see Observational studies: Does the language fit the evidence? Association vs. causation.

But some ended up pulling their punches with expert comments that overreached.

The Reuters Health story started off strong by noting that the study was not designed to “prove that skipping breakfast directly causes heart problems.” It also offered up an alternative explanation: “…some people may have been skipping breakfast because they were obese and were trying to lose weight or improve other risk factors for heart disease…”

In a subsequent paragraph, however, the story practically erased its own caveat by using this quote from the author of an accompanying editorial in the same issue of the Journal of the American College of Cardiology: “Indeed, these studies have proved the age old concept that breakfast is the most important meal of the day.” 

Actually, no. It doesn’t prove anything. 

Likewise, the Consumer Reports story gives readers similar whiplash in a single paragraph with the help of a quote from the study’s senior author: 

And though this study can’t directly prove cause and effect, the takeaway message on the importance of a healthy breakfast is clear. “If you introduce a good quality breakfast into your diet, it will probably help correct unhealthy behaviors later in the day,” Peñalvo says. “It’s a simple change that has the potential to change a whole lifestyle.”

No, again. The study didn’t measure the effect of eating breakfast on healthy behaviors. 

Just because an expert source says it, doesn’t make it true. And the expert sources quoted here were either authors of the study or of the editorial, who presumably have a vested interest in publicizing their work. None of the four news reports we read quoted independent sources with regard to the study findings. (Reuters Health and Consumer Reports did quote nutritionists about healthy breakfast tips.)  

Other limitations of the study

The people who skipped breakfast also had a bunch of other unhealthy habits — their diets were nutritionally poorer, they drank more alcohol, and they were more likely to be smokers than the breakfast eaters.

“Some reporters did a pretty good job pointing out that the breakfast skippers had other unhealthy behaviors,” Webster says. And while the study controlled for some of these, “there may still be residual confounding factors,” she says, meaning there might be other factors that researchers didn’t measure and thus didn’t account for, such as physical activity levels or sleep quality.

Several news stories included the fact that only 3 percent of participants fell into the breakfast-skipping category. But only the Forbes story called this out as a limitation.

It makes the margin of error wider,” says Webster.

Not only did Forbes call out a limitation others missed, it also left readers with a takeaway appropriate to the evidence presented. 

So if you currently eat a fairly healthy breakfast, continue on. Those who skip it and are healthy in general may be OK to continue if it works for them. Do what feels right for your body. 

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