Just like Grandma served.

I’ve always believed that breakfast is the most important meal of the day. Why? Because my mother told me so. Why did she believe it? Because her mother told her so. Who told her? Probably Edward Bernays, “the father of public relations.”

Is it true that breakfast is the most important meal of the day? Well, maybe not. If not, I’ve been self-herding for most of my life. I reached a decision (without much thinking) that breakfast was important. My only evidence was my mother’s advice.

Making the decision may have been a mistake. But, c’mon … she was my Mom. The more egregious mistake is that I never doubled back on the decision to see if anything had changed. I made the decision and never thought about it again. I self-herded into a set of fixed behaviors.

I also suffered from the confirmation bias. Researchers published articles from time to time confirming that breakfast is important. These studies confirmed what I already believed. Since the studies didn’t challenge my mental framework, I didn’t bother to check them closely. I just assumed that they were good science.

As it turns out, those studies were based on observations. Researchers observed people’s behavior and noted that people who ate breakfast were also generally healthier and less likely to be obese compared to people who didn’t. Clearly, breakfast is important.

But let’s think about this critically. There are at least three possible relationships between and among the variables:

• Eating breakfast causes people to be healthier – breakfast causes health
• Healthier people eat breakfast more than unhealthy people – health causes breakfast
• Healthier people eat breakfast and also do other things that contribute to good health – hidden variable(s) lead to healthiness and also cause people to eat breakfast.

With observational studies, researchers can’t easily sort out what causes what.

So James Betts and his colleagues did an experimental study – as opposed to an observational study – on the relationship between breakfast and good health. (The original article is here. The popular press has also covered the story including the New York Times, Time magazine, and Outside magazine).

Betts’ research team randomly assigned people to one of two groups. One group had to eat breakfast every day; the other group was not allowed to do any such thing. This isolates the independent variable and allows us to establish causality.

The trial ran for six weeks. The result: nothing. The researchers found no major health or weight differences between the two groups.

But previous research had found a correlation between breakfast and good health. So what caused what? It was probably a cluster of hidden variables. Betts noted, for instance, “…the breakfast group was much more physically active than the fasting group, with significant differences particularly noted during light-intensity activities during the morning.”

So it may not be breakfast that creates healthier outcomes. It may be that breakfast eaters are also more physically active. Activity promotes wellness, not breakfast.

If that’s true, I’ve been self-herding for many years. I didn’t re-check my sources. If I had, I might have discovered that Edward Bernays launched a PR campaign in the 1920s to encourage people to eat a hearty breakfast, with bacon and eggs. Bernays was working for a client – Beech-Nut Packing Company – that sold pork products, including bacon. I suspect the campaign influenced my grandmother who, in turn, influenced my mother who, in turn, influenced me. The moral of the story: check your sources, re-check them periodically, and be suspicious of observational studies. And don’t believe everything that your mother tells you.

(By the way, I recently published two short articles about the effects of chocolate and sex on cognition. Both of these articles were based on observational studies. Caveat emptor).