You’ve probably heard the rule that it’s okay to eat pretty much anything—even the bad stuff—as long as you eat it “in moderation.” Chicken breasts and spinach? In moderation. Bacon cheeseburgers and pound cake? Same theory applies.
But new research suggests that a more varied diet also tends to be a more unhealthy diet—at least when it comes to your waist size, according to new research from University of Texas Health Science Center at Houston and the Friedman School of Nutrition Science and Policy at Tufts University.
In the study, which was published in the journal PLOS ONE, researchers looked at data from 6,814 participants in the Multi-Ethnic Study of Atherosclerosis to determine the “diversity” of the participants’ diets—measured by factors like how many different foods they ate in a week, how many calories were consumed in the average food item, and the range of healthy foods versus unhealthy foods.
The researchers then looked at how those diets affected participants’ waistlines after five years. (“Waist circumference is an important indicator of central fat and metabolic health,” the study notes, in case you’ve somehow missed all those diet-plan commercials featuring retired NFL commentators.)
The results: After five years, participants who ate the widest variety of food had gotten the widest, gaining 120% more in waist size than study participants who had much less varied diets.
“An unexpected finding was that participants with greater diversity in their diets… actually had worse diet quality,” wrote lead study author Marcia C. de Oliveira Otto, Ph.D., of UTHealth. “They were eating less healthy foods, such as fruits and vegetables, and more unhealthy foods, such as processed meats, desserts and soda.”
So while the participants may have been eating everything in moderation, they still ate everything—including unhealthy junk.
“Americans with the healthiest diets actually eat a relatively small range of healthy foods,” said Dariush Mozaffarian, M.D., Dr.P.H., a senior study author and the dean of the Friedman School.
What to eat, then? You could start with our list of the 20 fittest foods you can pile on your plate, while making sure to avoid the eight absolute worst foods you can pump into your body. Steer clear of these 20 foods that seem healthy but aren’t, burn more fat with these tasty everyday fruits, and make sure you make room for these 10 superfoods people have totally forgotten about.