The Futile Cycle

A lot of news stories are once again talking about breakfast and its connections to weight and obesity. Consider this BBC article as one example. This Reuters article hypes breakfast as magically keeping teens skinny. The original Pediatrics journal article is here.

What’s wrong with all of this? The research doesn’t say whether eating breakfast makes someone lose weight. All it says is that skinnier teens eat breakfast more often than more obese teens, on average. That doesn’t mean that suddenly eating breakfast more will make you lose weight.

Consider, these details in the paper. People who eat breakfast more also: “more likely to be white, to come from a higher [socio-economic status], and to engage in higher levels of physical activity.” Hmmm, breakfast-eaters do more exercise, huh? I wonder if that has anything to do with the difference in weight…hey, will eating breakfast also make me white and wealthy? Awesome!

Sure, the authors try to correct for the physical activity differences in their regression, but no regression is perfect, and since all of the data is essentially self-reported, it’s hard to tell whether hours spent per week in “strenuous, moderate, and mild exercise” is really a good reflection of lifestyle choices. Maybe they take the stairs more often, or bike and walk more than those who don’t eat breakfast. Is running a mile moderate, strenuous, or mild exercise?

In addition, there are the classic correlation-versus-causation arguments: perhaps people who eat breakfast are just those who tend to have a higher metabolism naturally, and so they have the energy in the morning to get up early enough to eat breakfast. Or perhaps breakfast eaters are just more conscientious of their life choices, including sleeping, planning ahead, being less stressed, and so on, which might contribute to their lower BMI. Their eating breakfast in the morning could then be just one more symptom of their conscientiousness.

Though this article was published in the journal called Pediatrics, really this is just a sociological or economic study, not a medical study. Researchers and the news should stop hyping it as some sort of recommendation for preventing obesity. Breakfast isn’t a therapy just yet.

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Timlin, M.T., Pereira, M.A., Story, M., Neumark-Sztainer, D. (2008). Breakfast Eating and Weight Change in a 5-Year Prospective Analysis of Adolescents: Project EAT (Eating Among Teens). PEDIATRICS, 121(3), e638-e645. DOI: 10.1542/peds.2007-1035

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