Glycemic load, glycemic index, bread and incidence of overweight/obesity in a Mediterranean cohort: the SUN project

BACKGROUND: To evaluate prospectively the relationship between white, or whole grain bread, and glycemic index, or glycemic load from diet and weight change in a Mediterranean cohort. METHODS: We followed-up 9 267 Spanish university graduates for a mean period of 5 years. Dietary habits at baseline were assessed using a semi-quantitative 136-item food-frequency questionnaire. Average yearly weight change was evaluated according to quintiles of baseline glycemic index, glycemic load, and categories of bread consumption. We also assessed the association between bread consumption, glycemic index, or glycemic load, and the incidence of overweight/obesity. RESULTS: White bread and whole-grain bread were not associated with higher weight gain. No association between glycemic index, glycemic load and weight change was found. White bread consumption was directly associated with a higher risk of becoming overweight/obese (adjusted OR (≥2 portions/day) versus (≤1 portion/week): 1.40; 95% CI: 1.08-1.81; p for trend: 0.008). However, no statistically significant association was observed between whole-grain bread, glycemic index or glycemic load and overweight/obesity. CONCLUSIONS: Consumption of white bread (≥2 portions/day) showed a significant direct association with the risk of becoming overweight/obese.