School randomised trial on prevention of excessive weight gain by discouraging students from drinking sodas

To determine whether an educational programme aimed at discouraging students from drinking sugar-sweetened beverages could prevent excessive weight gain.

Forty-seven classes in twenty-two schools were randomised as intervention or control.

Participants were 1140, 9-12-year-old fourth graders (435 in the intervention 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 = weight (kg)/height (m2)), 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.

A statistically significant decrease in the daily consumption of carbonated drinks in the intervention compared to control (mean difference = -56 ml; 95 % CI -119, -7 ml) was followed by a non-significant overall reduction in BMI, P = 0.33. However, among those students overweight at baseline, the intervention group showed greater BMI reduction (-0.4 kg/m2 compared with -0.2 kg/m2 in the control group (P = 0.11)), and this difference was statistically significant among girls (P = 0.009). Fruit juice consumption was slightly increased in the intervention group (P = 0.08), but not among girls.

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.