BACKGROUND: Epidemiologic and experimental studies suggest that higher intake of dairy products could be associated with lower risk of hypertension and obesity. Differences in nutrient composition of distinct dairy products suggest that their effect on these outcomes might be heterogeneous. However, little experimental research has examined the potentially different effects of low- and whole-fat dairy products on blood pressure (BP) and weight change. The present study aimed to assess whether supplementing diets with low- or whole-fat dairy products would differentially affect BP levels and weight. METHODS: A randomised crossover trial in 45 normotensive volunteers (18-24 years old, 49% female) was conducted. Participants alternatively received 3.5 servings/day of whole-fat or low-fat dairy products (milk and yogurt) in addition to their usual diet during two 8-week periods, with a 4-week washout period between both interventions. Weight and BP were measured at the beginning and end of each intervention. RESULTS: Whole-fat dairy supplementation significantly increased systolic BP [2.1 mmHg, 95% confidence interval (CI) = 0.1-4.0, P = 0.04] and weight (1.0 kg, 95% CI = 0.5-1.5, P = 0.0002), but not diastolic BP (P = 0.34). Weight and BP did not change significantly after the low-fat dairy intervention (P > 0.10). There were no significant differences in the effect of low-fat or whole-fat dairy products on BP (P > 0.60), but whole-fat dairy increased weight significantly compared to low-fat dairy (1.2 kg, 95% CI = 0.5-1.8, P = 0.0007). CONCLUSIONS: In a young nonhypertensive population, dietary supplementation with whole-fat dairy products, compared to low-fat dairy, was associated with weight gain. No differential effects were observed for levels of BP.