For years you’ve been told to go for skim over full-fat dairy. Even the latest dietary guidelines for Americans urge people to avoid the full fat, and following this lead, school lunch programs provide only low-fat milk and no whole milk at all, even though they do allow chocolate skim milk with its added sugars. But large population studies that look at possible links between full-fat dairy consumption, weight and disease risk are starting to call that advice into question. And some research suggests people who consume full-fat dairy weigh less and are less likely to develop diabetes, too.

In a new study published in the journal Circulation, Dr. Dariush Mozaffarian and his colleagues analyzed the blood of 3,333 adults enrolled in the Nurses’ Health Study of Health Professionals Follow-up Study taken over about 15 years. They found that people who had higher levels of three different byproducts of full-fat dairy had, on average, a 46% lower risk of getting diabetes during the study period than those with lower levels. “I think these findings together with those from other studies do call for a change in the policy of recommending only low-fat dairy products,” says Mozaffarian. “There is no prospective human evidence that people who eat low-fat dairy do better than people who eat whole-fat dairy.”

Since full-fat dairy products contain more calories, many experts assumed avoiding it would lower diabetes risk. But studies have found that when people reduce how much fat they eat, they tend to replace it with sugar or carbohydrates, both of which can have worse effects on insulin and diabetes risk. In the current study, Mozaffarian adjusted for the role that weight plays, and found the connection between full-fat dairy intake and lower diabetes risk remained strong independent of weight gain.

In fact, in a separate study published in the American Journal of Nutrition, another group analyzed the effects of full fat and low fat dairy on obesity and found that among 18,438 women in the Women’s Health Study, those who consumed the most high-fat dairy products lowered their risk of being overweight of obese by 8%.

Together, the body of data is beginning to reveal both that full-fat dairy has a place in a healthy diet, and also how focusing on one nutrient in the diet may backfire. When dietary guidelines began urging people to lower the amount of fat they ate, the idea was to reduce the amount of cholesterol and unhealthy fats in the body. But by focusing just on cutting out fat, experts didn’t count on the fact that people would compensate for the missing fat and start loading up on carbohydrates, which the body converts into sugar—and then body fat.