ABSTRACT Background: A diet with a high glycemic index (GI) and glycemic load (GL) may promote overconsumption of energy and increase the risk of weight gain.Objective: The objective of the study was to investigate the relation between GI and GL of habitual diets and subsequent 6-y changes in body weight, body fat distribution, and body composition in a random group of adult Danes. Design: A prospective cohort study was conducted in a subsample of men and women from the Danish arm of the Monitoring Trendsand Determinants in Cardiovascular Disease study. The ubsample comprised 185 men and 191 women born in 1922, 1932, 1942, or 1952. A baseline health examination and a dietary history interview were carried out in 1987 and 1988; a follow-up health examination was performed in 1993 and 1994. Results: Positive associations between GI and changes in bodyweight (¿BW), percentage body fat (%BF), and waist circumference (¿WC) were observed in women after adjustment for covariates.Significant GI X sex X physical activity interactions for ABSTRACTBackground: A diet with a high glycemic index (GI) and glycemicload (GL) may promote overconsumption of energy and increase therisk of weight gain.Objective: The objective of the study was to investigate the relationbetween GI and GL of habitual diets and subsequent 6-y changes inbody weight, body fat distribution, and body composition in a randomgroup of adult Danes.Design: A prospective cohort study was conducted in a subsampleof men and women from the Danish arm of the Monitoring Trendsand Determinants in Cardiovascular Disease study. The subsamplecomprised 185 men and 191 women born in 1922, 1932, 1942, or1952. A baseline health examination and a dietary history interviewwere carried out in 1987 and 1988; a follow-up health examinationwas performed in 1993 and 1994.Results: Positive associations between GI and changes in bodyweight (¿BW), percentage body fat (¿%BF), and waist circumference(WC) were observed in women after adjustment for covariates.Significant GI X sex X physical activity interactions for ¿BW,¿%BF, and ¿WC were observed, and the associations in the sedentarywomen were particularly positive. No significant associationswith GI were observed in men, and no significant associations withGL were observed in either sex.Conclusions: High-GI diets may lead to increases in BW, body fatmass, and WC in women, especially in sedentary women, whichsuggests that physical activity may protect against diet-inducedweight gain. No associations with GI were observed in men, whichsuggests sex differences in the association between GI and obesitydevelopment.