On any given day in normal life, nearly one-third of American adults opt for the convenience of a meal prepared in a kitchen that’s not their own, a choice that can make it harder to stick to a healthy eating pattern.

Researchers at the Friedman School of Nutrition Science and Policy at Tufts University in Boston analyzed the dining choices of more than 35,000 Americans over a 24-hour period. The scientists then assessed the nutritional quality of food from full-service restaurants (those with wait staff) versus fare from fast-food and fast-casual venues—only to discover that 70% of meals procured at fast-food and casual joints had poor nutritional value.

For full-service restaurants, around half of the meals were determined to be nutritionally lackluster. Worse still, fewer than 0.1% of the restaurant meals analyzed during the study period—2003–2016—provided ideal nutritional quality, as measured using an American Heart Association diet score.

Restaurant meals accounted for a whopping 21% of Americans’ total calorie intake. Since these findings drive home the point that dining out remains so prevalent and is a recipe for unhealthy eating the majority of the time, people should continue to receive  education on how to spot healthier options on menus and get encouragement to prepare most of their meals at home.