Objective: Previous studies have shown that stunting increases the risk of obesity in developing countries, particularly among girls and women, but the underlying reasons are not known. This study aimed to investigate the relationship between stunting, weight gain, and resting metabolic rate. Design and subjects: A prospective study was conducted over 36 months with girls from shantytowns in São ... [Show full abstract] Paulo, Brazil. A total of 15 stunted girls (S) were compared with 15 nonstunted (N) ones of similar weight for height ratio. Interventions: Resting metabolic rate was measured using indirect calorimetry, and the socioeconomic status was determined by interviews in the household. In addition, body composition was measured by skinfold thickness, while the growth rate was calculated dividing the change in weight and the change in height by the follow-up period. Results: The results of the present study, when combined, revealed that the S group had a lower resting metabolic rate throughout the follow-up period with the differences being significant at 24 and 36 months of follow-up, associated with an increase in the rate of weight gain and a decrease in lean mass, when compared to the N group. Conclusions: These changes are known to be risk factors for obesity and may help to explain the particularly higher prevalence of obesity in women in urban areas of developing countries.