Eating out is often a recipe for an unhealthy diet, a new study confirms.

Going out definitely has its perks. For one, you don’t need to make your own food. You can also taste all sorts of varied foods, and hopefully enjoy a relaxing time with pleasant company.

But eating out might be costly in more than one way. A new study analyzed the dietary selections of more than 35,000 U.S. adults from 2003-2016. The study participants dined at full-service (those with wait staff) or fast-food restaurants, which included pizza shops.

Researchers analyzed the nutritional quality of the participants’ foods, using the diet score of the American Heart Association.

They found that, unsurprisingly, meals from fast food places are most often unhealthy. Some 70% of the meals Americans ate in fast foods in 2015-2016 have poor dietary quality — but on the positive side, this figure is down from 75% in 2003-2004, when a similar study was carried out.

Things were better, but still not good, in full-service restaurants. Half of the meals served in such restaurants were of poor nutritional quality, and this figure has remained constant in recent years.

It’s not like the other half was particularly good, either: less than 0.1% of all restaurant meals were of ideal quality. This is concerning, and it shows that rarely, if ever, are restaurant meals healthy.

“Our findings show dining out is a recipe for unhealthy eating most of the time,” said Dariush Mozaffarian, senior author and dean of the Friedman School. “It should be a priority to improve the nutritional quality of both full-service and fast-food restaurant meals, while reducing disparities so that all Americans can enjoy the pleasure and convenience of a meal out that is also good for them.”

There were also notable racial differences, as some groups are starting to reduce the number of meals consumed at restaurants. For instance, non-Hispanic whites and Mexican-Americans had a lower calorie intake coming from restaurants, whereas non-Hispanic blacks did not. In addition, the proportion of poor-quality fast-food meals decreased slightly for people with college degree, while for people without a college degree, it remained stable.

Researchers also made recommendations on how to improve restaurant meals and make them healthier.

“We found the largest opportunities for enhancing nutritional quality would be adding more whole grains, nuts and legumes, fish, and fruits and vegetables to meals while reducing salt,” said first author Junxiu Liu, a postdoctoral scholar at the Friedman School.

Food is an extremely important factor in human health, but we often don’t pay it sufficient attention. In 2019, figures from the CDC found that more than one-third (36.5%) of U.S. adults age 20 and older are obese, along with 17% of children and adolescents aged 2–19 years. This isn’t just a major health cost, but also a massive expenditure cost. An obese person in the United States incurs an average of $1,429 more in medical expenses annually, which adds up to approximately $147 billion in added medical expenses per year — within the United States alone.

Eating out, researchers explain, is an important part of the problem — but it can also be a part of the solution.

“Our food is the number one cause of poor health in the country, representing a tremendous opportunity to reduce diet-related illness and associated healthcare spending,” Mozaffarian concludes. “At restaurants, two forces are at play: what’s available on the menu, and what Americans are actually selecting. Efforts from the restaurant industry, consumers, advocacy groups, and governments should focus on both these areas.”

The study has been published in The Journal of Nutrition.