At some point in your life, you’ve probably been subjected to the counterintuitive notion that skipping breakfast can actually lead to weight gain. This idea has become so pervasive that in 2010 the government began including it in U.S. Dietary Guidelines.

Eat a nutrient-dense breakfast. Not eating breakfast has been associated with excess body weight, especially among children and adolescents. Consuming breakfast also has been associated with weight loss and weight loss maintenance.

But researchers from Columbia University who studied the long-accepted belief found that “in overweight individuals, skipping breakfast daily for 4 weeks leads to a reduction in body weight.”

To make matters worse, the government’s method for adopting the breakfast guidelines were based on “loose scientific guesses” rather than hard evidence, according to The Washington Post’s Peter Whoriskey. This is due to the reliance on “observational studies” as opposed to more controlled research studies.

One of the primary troubles in observational studies is what scientists refer to as “confounders” — basically, unaccounted factors that can lead researchers to make mistaken assumptions about causes. For example, suppose breakfast skippers have a personality trait that makes them more likely to gain weight than breakfast eaters. If that’s the case, it may look as if skipping breakfast causes weight gain even though the cause is the personality trait.

In analyzing the results of observational studies, scientists make statistical adjustments to adjust for the potential confounding factors that they can measure — age, alcohol consumption, exercise, employment, and the like. Breakfast skippers in the health professionals study, for example, tended to drink more, smoke more, and exercise less. The scientists adjusted their statistics accordingly. But the adjustments are imprecise, and there is no guarantee that the groups are not different in some other unmeasured way.

Later this year, the government will release updated 2015 Dietary Guidelines, so there is a chance the questionable information about skipping breakfast and weight gain may be removed. But regardless, it’s important to remember to take such proclamations with a grain of salt.

Or maybe take it without salt, depending on whom you believe.

(Source: Peter Whoriskey/The Washington Post)