The world of dieting is awash in half-truths and wishful thinking. Just have a look at some of these fad diets to be reminded of how much we are willing to stretch reason in pursuit of weight loss.
David Allison, a researcher and director of the Nutrition Obesity Research Center at the University of Alabama, Birmingham, is fascinated by the mountain of myths and assumptions about what makes us fat. Lately, he's turned his attention to understanding why so many researchers recycle these myths despite the lack of good evidence supporting them.
In a paper out this week in the American Journal of Clinical Nutrition, Allison and colleagues examine the long-running presumption that it's better to eat breakfast than to skip it if you want to lose weight. They found that this presumption is common in obesity research, and it's usually a result of researchers' bias — when describing their own or others' work.
But wait a second. Does that mean there is zero connection between breakfast and weight? No, says Allison.
"Studies show there is an association between regularly skipping breakfast and higher body mass index," Allison tells The Salt. "But it is an association, so it does not necessarily represent cause and effect."
(There's also an association between skipping breakfast and a higher risk of heart attack, as Allison Aubrey reported in July.)
The only way to truly understand cause and effect is with a randomized control trial — the gold standard for clinical research. Only one such study — conducted in 1992, with 52 women participating — hinted at a link between breakfast and weight change, he says, and no similar trials have been done since then.
But in the meantime, Allison says, hundreds of papers have presumed that skipping breakfast does affect weight.
So why are researchers so susceptible to repeating unproved ideas? Allison says he hasn't studied this question specifically, but he can speculate.
"We all eat, and we all have beliefs about food, family, morals and body weight," he says. "It's a very emotional issue for many people, and some of that leads to ... passion that sometimes clouds judgment."
And the breakfast-skipping hypothesis is far from the only one out there that needs better testing. Earlier this year, Allison and some colleagues published a paper in the New England Journal of Medicine detailing seven big myths about obesity.
Allison isn't just complaining; he's doing something to address the situation. Since there is no big controlled trial on the effect of breakfast on weight loss, he has one in the works. It will involve 300 adults at six sites around the country. He says he hopes to have results in six months.