The consumption of low-fat and full-fat dairy is associated with decreased adiposity in observational studies. In randomized controlled trials, dairy foods have no impact on body weight or result in a modest weight increase in ad libitum studies. We aimed to test the effects of diets rich in low-fat or full-fat milk, yogurt, and cheese on energy homeostasis, compared to a diet limited in dairy.
72 participants with the metabolic syndrome completed a 4-week wash-in period, during which their dairy intake was limited to ≤ 3 servings of skim milk per week. Participants were then randomized to either continue the limited dairy diet or switch to a diet containing 3.3 servings per day of either low-fat or full-fat dairy products for 12-weeks. Measures of adiposity were assessed before and after the intervention period, and the effect of adding dairy foods to a standardized diet on ad libitum energy intake were assessed during two 5-day controlled feeding periods.
In the per protocol analysis (n=66), overall repeated measures analysis of variance revealed a significant diet effect on body weight and waist circumference (p=0.005 and p=0.015 respectively), with a significant increase in body weight in the full-fat dairy group compared to the limited dairy group, as well as a significant increase in waist circumference in the low-fat dairy group and the full-fat dairy group compared to the limited dairy group. There was no diet effect on hip circumference, waist to hip ratio, fat mass, trunk fat, or peripheral fat. Ad libitum energy intake during the controlled feeding periods was greater when the diets included full-fat dairy foods compared to the control diet limited in dairy (p<0.001).
In individuals with the metabolic syndrome, consuming 3 servings of dairy per day resulted in increased body weight and waist circumference compared to a diet limited in dairy, with no difference between low-fat and full-fat dairy groups.