Purpose: High-glycemic index (GI) diet has been associated with obesity, but epidemiological data are inconsistent. We therefore investigated the relation between GI and glycemic load (GL) with body mass index (BMI) and waist to hip ratio (WHR), as a measure of body fat distribution.
Methods: We analysed data from the control group of a network of hospital-based case-control studies from Italy. A total of 7,724 patients (3,482 men, 4,242 women; age range 18-82 years) were interviewed using a validated 78-item food-frequency questionnaire.
Results: Mean BMI decreased from the lowest to the highest tertile of GI from 26.59 to 26.18 kg/m² in men (p ~ 0.005), and from 25.81 to 25.09 kg/m² in women (p < 0.001). With respect to GL tertiles, the corresponding values were 26.41 and 26.25 kg/m² in men (p ~ 0.51), and 26.01 and 24.93 kg/m² in women (p < 0.001). Using linear regression models including terms for major potential confounding factors and energy intake, GI and GL were inversely related to BMI: the coefficients (for the highest compared to the lowest tertile) were -0.46 among men and -0.81 among women for GI, and -0.79 and -1.33 for GL. No consistent association was found with WHR.
Conclusions: GI and GL were, if anything, inversely related to BMI and WHR in this Italian population.