The rising popularity of intermittent fasting has many Americans forgoing meals, but the USDA’s Economic Research Service has some insight you don’t want to miss: While skipping a meal can slash daily calorie intake, it can also reduce overall diet quality—especially if the meal you miss is breakfast or lunch.

Using 2 days of food intake data gleaned from the 2007–2016 National Health and Nutrition Examination Survey, investigators determined that skipping a meal reduced daily caloric intake in adults by between 252 calories (breakfast) and 350 calories (dinner). Based on the Healthy Eating Index, however, skipping breakfast or lunch decreased diet quality by about 2.2 points, while skipping dinner lowered it by 1.4 points. (The HEI is a measure of how well a person’s diet conforms with recommendations in the Dietary Guidelines for Americans.) Scores for fruit, whole grains and dairy took the biggest hits when one of the first two meals of the day was axed.

The takeaway is that if people are practicing a form of fasting, they need to be properly educated on how to meet all their nutrition needs at the meals they are consuming, especially if they skip breakfast or lunch.

See also: The Art and Science of Intermittent Fasting