Researchers at Northwestern University have found that the longer someone sleeps in, the more likely they are to wake up and head for the drive-thru window.

By Gillie Houston
Updated May 24, 2017
Credit: © Bloomberg via Getty Images

If you take weekend mornings as an opportunity to sleep in, you may be dismayed to learn about a new study. Researchers at Northwestern University have found that the longer someone sleeps in, the more likely they are to eat fast food.

Published in the journal aptly called Sleep, the study draws a correlation between the hour we rise with how healthful our dietary choices are. Scientists monitored a group of 96 participants between the ages of 18 and 50, each of whom slept at least six-and-a-half hours every night. Over the course of the week, the subjects kept detailed food diaries and had their body fat and level of physical activity monitored.

Not only did the researchers discover that participants who slept until later in the morning were more likely to turn to fast food for meals, but those subjects also had more sedentary lifestyles and tended to consume less vegetables.

"Our results help us further understand how sleep timing in addition to duration may affect obesity risk," says Kelly Glazer Baron, lead investigator and professor of neurology at Northwestern. In the past, Baron has also lead studies that have found that eating after 8 p.m. and staying up late lead to lower fruit and vegetable consumption and an average of 248 more calories consumed per day.

"The extra daily calories can mean a significant amount of weight gain—two pounds per month—if they are not balanced by more exercise," Baron says. Of her most recent study, the researcher concludes that "it is possible that poor dietary behaviors may predispose individuals with late sleep to increased risk of weight gain."

As always, correlation is not causation. It's not hard to imagine that weekend early risers might be a bit more predisposed toward healthy food in general. There's plenty of evidence that getting lots of sleep is good for your health. And if your choice is between sleeping late and spending a Saturday sleep-deprived, you should know about the conclusion of a different recent study: Sleep loss gives you the munchies. Apparently, you can't win.