Dairy consumption and body mass index: an inverse relationship

To assess the relationship between consumption of dairy products and body mass index (BMI) in Tehranian adults.

Cross-sectional study.

A total of 462 healthy subjects (223 men and 239 women) aged over 16 y selected randomly from among participants of the Tehran Lipid and Glucose Study (TLGS).

Dietary data were collected by means of a food frequency questionnaire for 1 y and two 24-h dietary recalls. Height and weight were measured and BMI was calculated. Physical activity was assessed by the Lipid Research Clinic (LRC) questionnaire.

Consumption of dairy products was 3.7+/-1.0 and 2.9+/-1.2 servings per day in men and women, respectively. As the servings of dairy consumption increased per day, the proportion of normal-weight subjects rose and that of obese ones declined. As BMI increased, the proportion of subjects with lower consumption of dairy products increased, whereas that of those with higher consumption decreased. There was a significant inverse correlation between the servings of dairy consumption per day and BMI after controlling for the effect of age, physical activity, energy, carbohydrate, dietary fiber, protein and fat intake (r=-0.38, P<0.05). After adjustment for potential confounding variables, men and women in the top quartile of dairy consumption had lower chances for being overweight (OR=0.78, 95% CI=0.43-0.92 for men and OR=0.89, 95% CI=0.53-0.95 for women) and obese (OR=0.73, 95% CI=0.40-0.83 for men and OR=0.69, 95% CI=0.34-0.80 for women) compared to those in the first quartile.

The results suggest an inverse relationship between dairy consumption and BMI. It is recommended that further studies address this issue by focusing on the dairy components responsible for this effect.