A morning glass of milk may keep you from eating too much at lunchtime, according to new research.

RODALE NEWS, EMMAUS, PA—According to a new study published in the American Journal of Clinical Nutrition, drinking milk in the morning may keep you from overeating at lunch.

THE DETAILS: Researchers from New Zealand recruited 34 overweight men and women in two different sessions. The groups were divided in half, with each fed a breakfast with the same number of calories. One group was given about 20 ounces of a fruit drink, and the other group was given 20 ounces of skim milk (the fruit drink and the milk had approximately the same number of calories). Four hours later, the groups were fed lunch, which consisted of various types of sandwiches, and were instructed to eat until they felt full. During both sessions, the group that had milk with breakfast consumed about 55 fewer calories at lunch than the group that had fruit juice. Furthermore, the milk group scored 9 to 11 points higher when they were asked how full and satisfied they were after breakfast.

WHAT IT MEANS: The researchers weren’t able to identify the exact component of milk that allowed people to feel fuller and eat less later in the day, but they theorize that it has something to do with milk’s protein content—protein is more filling than the carbohydrates in fruit drinks—or its calcium content. While calcium hasn’t been directly linked to appetite control, it can impact your weight. “Not having enough calcium causes your body to secrete hormones that allow you to retain what calcium you do have,” says Michael Zemel, PhD, director of the University of Tennessee Nutrition Institute and the author of several other studies looking at dairy’s affect on weight management. Those hormones can cause you to gain weight, he notes. But dairy is a very complicated type of food, he adds, so it’s hard to know exactly what’s going on. “There are components of dairy other than calcium that have metabolic affects,” he says.

“What all this comes down to is that milk is part of a healthy diet,” Zemel says. You can’t boil its calorie-control benefits down to a single component, but you can benefit from all its components by including healthy dairy products in your diet.