Public Health Nutrition: 12(2), 197–202 doi:10.1017/S1368980008002644 School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas Rosely Sichieri 1, *, Ana Paula Trotte 1 , Rita Adriana de Souza 1 and Gloria V Veiga 2 1 Department of Epidemiology, Institute of Social Medicine, State University of Rio de Janeiro, Rua Sa ˜o Francisco Xavier, 524, 78 andar, Bloco E. Cep 20550-012, Rio de Janeiro, RJ, Brazil: 2 Department of Nutrition, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil Submitted 9 October 2007: Accepted 3 April 2008: First published online 18 June 2008 Abstract Objective: To determine whether an educational programme aimed at discoura- ging students from drinking sugar-sweetened beverages could prevent excessive weight gain. Design: Forty-seven classes in twenty-two schools were randomised as inter- vention or control. Subjects: Participants were 1140, 9–12-year-old fourth graders (435 in the inter- vention group and 608 in the control group). Sugar-sweetened beverages and juice intake were measured through one 24 h recall at baseline and another at the end of the trial. The main outcome was the change in BMI (BMI 5 weight (kg)/height (m 2 )), measured at the beginning and at the end of the school year. Intention- to-treat analysis was performed taking into account the cluster (classes) effect. Results: A statistically significant decrease in the daily consumption of carbonated drinks in the intervention compared to control (mean difference 5256 ml; 95 % CI 2119, 27 ml) was followed by a non-significant overall reduction in BMI, P 5 0?33. However, among those students overweight at baseline, the intervention group showed greater BMI reduction (20?4 kg/m 2 compared with 20?2 kg/m 2 in the control group (P 5 0?11)), and this difference was statistically significant among girls (P 5 0?009). Fruit juice consumption was slightly increased in the intervention group (P 5 0?08), but not among girls. Conclusion: Decreasing sugar-sweetened beverages intake significantly reduced BMI among overweight children, and mainly among girls. Efforts to reduce energy intake through liquids need to emphasise overall sweetened beverages and addition of sugar on juices. Keywords Randomised controlled trial Obesity Children Carbonated beverages Brazil Obesity is a major public health problem in many coun- tries throughout the world, especially for the young population and for the poor (1) . In Brazil, obesity and overweight have been increasingly common in adults (2) , as well as in adolescents (3) . Dietary interventions that could prevent excessive weight gain in adolescents are fundamental to curb this epidemic. School is considered a suitable setting for the promo- tion of healthy lifestyles in children (4,5) . For obesity pre- vention many programmes have been tested among schoolchildren. Usually, these programmes have multiple focuses, including physical activity and nutritional beha- viours, and most of them have attained good results in educating children on these issues (6,7) , but with little or no effect on weight change (7,8) . On the other hand, a randomised trial with British schoolchildren with a focus on reduction of carbonated sodas showed a statistically significant and clinically relevant reduction in the weight gain in the experimental group compared with con- trols (9) . The strategy for the study was to reduce overall energy intake by the substitution of sugar-sweetened beverages for non-caloric drinks. Several educational activities were employed in order to incorporate this message. Two other longitudinal studies conducted in the USA observed increased BMI and prevalence of over- weight associated with sugar-sweetened beverages (10–12) , and a review of sugar-sweetened carbonated beverages linked their intake to weight gain in both children and adults (13) . Although some educators think that schools already have too much to do, and that prevention of obesity should not be expected to be an added responsibility (14) , school is considered an important part in the effort to prevent childhood obesity (15) . Also, in countries such as Brazil, public schools are one of the few public institutions that reach the majority in the low socio-economic groups. *Corresponding author: Email sichieri@ims.uerj.br r The Authors 2008