For decades, it's been considered hard fact and common sense: Eating breakfast is a surefire way to kick-start your metabolism, and people who skip breakfast are more likely to gain weight.
But recent studies point to a murkier relationship between breakfast, metabolism, weight loss and health. What most people may not realize is that the science regarding breakfast's relationship with metabolism is shaky at best.
"Many — if not most — studies demonstrating that breakfast eaters are healthier and manage weight better than non-breakfast eaters were sponsored by Kellogg or other breakfast cereal companies whose businesses depend on people believing that breakfast means ready-to-eat cereal," New York University nutritionist Marion Nestle wrote last year on her blog, Food Politics, in response to a reader's question.
Some studies attempt to draw a link between skipping breakfast and poor health, like heart disease and weight gain. Others focus on total caloric intake, regardless of whether those calories are consumed as part of a hearty breakfast of eggs and bacon.
In 2014, as a new wave of diet fads advocated strict fasting regimens -- including fasting from 8 a.m. until lunch the next day -- personal trainer Jillian Michaels told an interviewer that calorie intake is more important than assigning arbitrary rules to certain meals, or skipping meals altogether.
Michaels said she still advises her clients not to eat sugary snacks before bed, but overall portion control has a greater impact on weight than skipping meals.
"I get the whole, 'Don't eat before bed' thing," Michaels said, "but to be truthful, all the current research is suggesting that it doesn't matter when you eat your food, as long as you're not overeating period."
That line of thinking is reflected in updated health guidelines from the federal government, including the Department of Health's 2015–2020 Dietary Guidelines for Americans.
Most nutrionists still recommend eating breakfast, and healthy meals to start the day are generally accepted as important for growing children, but better studies and better data have prompted experts to backtrack on the previous conventional wisdom about breakfast and weight loss.
Barbara Millen, chairwoman of the 2015 advisory committee for the department's dietary guidelines, told the Washington Post that it's more important to emphasize the kinds of foods people are eating -- and how much they eat.
"We didn’t want to focus on a laundry list of foods and meals," Millen told the Post. "We were focusing on overall dietary patterns.”