In 2015, the World Health Organization (WHO) recommended implementing measures worldwide to reduce the consumption of sugary drinks and their health consequences. WHO reports suggest that taxes on sugary drinks help reduce the consumption of these products and also the prevalence of obesity, type 2 diabetes and dental caries. However, the results derived from different studies of the implementation of this policy in different countries indicate controversial results. Therefore, the results of this publication are of great interest in order to obtain information to establish the effectiveness of policies that are being implemented globally to reduce sugar intake and the incidence of childhood obesity and chronic diseases in the future.The authors use data from the National Child Measurement Programme that began in 2006. The height and weight of primary school children aged 4 and 5 years and 10 and 11 years, respectively, were measured annually. The study was conducted to find out the levels of overweight and obesity in children. In 2016, a tax was imposed on sugary soft drinks in the UK. The authors examined the prevalence of obesity in selected populations for 19 months after the implementation of this measure. The effect of gender and household socio-economic status on childhood obesity was also assessed. The study concludes that the levy reduced the prevalence of obesity only in sixth-grade girls (10-11 years) living in areas with the worst economic conditions of those studied.

The results found by the authors indicate that the variables studied influence the outcome in line with previous studies. Not surprisingly, differences due to age and gender are found. The authors describe the strengths and limitations of the study and compare their results with similar studies. However, the size of the populations for each sex and age group is not clearly specified. Prevalence is mentioned and percentage data are given. There is no indication of how many pre-school or primary school children of each economic status participated in the study. Similarly, there is no indication of how the level of consumption of sugar-sweetened beverages by the populations studied has been assessed.

These factors could have an influence on the result to be taken into account in the interpretation of the results. Another aspect that could influence the result and has not been taken into account are the differences in the degree of hormonal development of the two groups of girls and boys. The girls in the sixth grade group may be past menarche, which may influence food intake and metabolism. As the authors acknowledge, further research is needed to understand the effectiveness of the sugar rate, but it is imperative to continue to emphasise the reduction of sugar intake in the whole population and most importantly in children and adolescents.