Another dietary conviction, born of observational studies and much conventional wisdom, has been routed in a randomized control trial. The belief that skipping breakfast is bad for you if you want to lose weight doesn’t hold up when subjected to a more rigorous study design, according to a more rigorously designed study—“The effectiveness of breakfast recommendations on weight loss: a randomized controlled trial,” published in the American Journal of Clinical Nutrition.
“We thought it was important to test this commonly held assumption,” said lead author Emily Dhurandhar by email, “since short-term studies suggest that eating breakfast may help regulate appetite and metabolism, it has often been assumed that this would translate to breakfast enhancing weight loss.”
The moral of the study: never assume.
Previously, only one randomized control trial published in 1992--Schlundt et al.—had investigated the impact of skipping versus eating breakfast among people seeking to lose weight. It found that the act of switching from breakfast to no breakfast or vice versa seemed to be driving weight loss compared to not changing breakfast behavior; and the more radical the change in behavior at breakfast time, the greater the weight loss. This study was widely reported in the scientific literature as having shown that eating breakfast led to weight loss, even though that is not what the authors concluded. Because Dhurandhar et al. used a much larger sample—they enrolled 309 subjects compared to 52 in the earlier study, they were able to do a better job of controlling for the effects of switching.
Among those people who were breakfast skippers when they started the program, the control group (those who were told only “eat healthy” and given a US Department of Agriculture pamphlet, but not given any instructions on eating or not eating breakfast) lost an average of 0.71 kg; but the standard deviation was 1.16 kg. This means that about 68 percent of this group experienced anything from a weight loss of 1.87 kg (.71+1.16kg), to a weight gain of .61 kg (.71 minus 1.16kg).
Similarly, if you were a breakfast skipper assigned to the group that was told to eat breakfast, you lost .76 kg on average, but the standard deviation was 1.26, so about two-thirds of people lost somewhere between 2.02 kg (76+1.26kg) or gained .50kg (1.26 minus .76kg).
Finally, those breakfast skippers who were told not to eat breakfast lost on average .61kg, but two-thirds of them lost as much as 1.79kg (.61+1.18kg) or gained as little as .57kg (1.18 minus .61kg)--or achieved something in between.
Those who were breakfast eaters were cast in similar groupings, with the same results: you see no effect of being a breakfast eater and not being told anything about breakfast (the control group), compared with the being told to eat breakfast group and the being told not to eat breakfast group.
As Dhurandhar put it, their study was all about timing: to eat or not to eat breakfast “didn’t influence weight loss in free-living people trying to lose weight on their own.” But, she added, that doesn’t mean that specific breakfast foods or eating a large breakfast wouldn’t be helpful for other reasons. The next step would be to repeat the experiment looking at effects on metabolic variables over a longer period of time relative to specific foods, something that would be expensive to do, but could yield important insights into whether all breakfast foods are equal, or whether there might be other more subtle changes related to skipping or not that are only revealed over a much longer duration. One might say, the “most important meal of the day”(sic) deserves nothing less.
