The Association Between Dietary Glycemic Index and Glycemic Load and a Body Shape and Fat Distribution Among Apparently Healthy Iranian Adults

Abstract

Objective: The role of dietary glycemic index (GI) and glycemic load (GL) in the development of obesity has been debated globally. The relationship with body shape and fat distribution was examined in this cross-sectional association study among apparently healthy Iranian adults.

Methods and materials: A study population of 265 (126 males and 139 females) aged 18-55 years participated in this cross-sectional study from the communities of Tehran based on cluster sampling. GI and GL were assessed by the 147-item food frequency questionnaire (FFQ) completed by a trained dietitian. Weight, height, waist circumference (WC), and hip circumference of the participants were measured, and body mass index (BMI), waist-to-hip ratio (WHR), and A Body Shape Index (ABSI) were further calculated. Fat mass and fat-free mass were also measured using a body composition analyzer, and fat mass index (FMI) and fat-free mass index (FFMI) were then calculated. Multivariate regression models were fitted to assess the association between GI/GL and fat distribution measures such as FMI, FFMI, WC, BMI, WHR, and ABSI, considering potential confounding factors such as sex, age, BMI, and physical activity.

Results: There was a statistically significant inverse association between GL and WC, BMI, and ABSI found in the adjusted model. GL was inversely associated with WC for both the adjusted model (p-trend = 0.027) and the crude model. Also, an inverse association was seen between GL and BMI (p-trend = 0.019) in the adjusted model but a marginal association in the crude model. GL was also inversely associated with ABSI (p-trend = 0.089) in the highest tertile.

Conclusion: Dietary GL but not GI is inversely associated with fat distribution measures such as WC, BMI, and ABSI in the study population. This result may suggest a beneficial role of higher-GL diets in the prevention of obesity.

Keywords: Glycemic index; a body shape index; body mass index; fat distribution; fat free mass; fat mass; glycemic load; obesity; waist circumference.