What is the aim of this review?

The aim of this Cochrane Review was to find out if healthy weight interventions can improve thinking skills and school performance in children and teenagers with obesity. Cochrane researchers collected and analysed all relevant studies to answer this question.

What are the key messages?

This updated review provides some evidence that school programmes that encourage healthier child weight may also provide ‘co-benefits’ of thinking skills and school performance. However, we need more high-quality healthy-weight interventions that test thinking skills and school performance, as well as health outcomes.

What was studied in this review?

The number of children and teenagers with obesity is high worldwide. Some children and teenagers with obesity have health issues or are bullied because of their body weight. These experiences have been linked to problems in performing well in school, where they tend to perform less well in thinking tasks such as problem-solving. Physical activity and healthy eating benefit a healthy body weight and improve thinking skills and school performance in children with a healthy weight. Studies found that healthy-weight interventions can reduce obesity in children and teenagers, but it is unknown if and how well healthy-weight interventions can improve thinking skills and school performance in children and teenagers with obesity.

What are the main results of this review?

The review authors found 18 studies which included a total of 2384 children and teenagers with obesity. Five studies assigned individual children to intervention or control groups. Thirteen studies allocated entire classes, school or school districts to the intervention and control group. Of the 18 studies, 11 involved children at primary/elementary-school age. Eight studies offered physical activity interventions, seven studies combined physical activity programmes with healthy lifestyle education, and three studies offered dietary changes. The studies took place in 10 different countries. Seventeen studies had at least one flaw in how the study was done. This reduces the level of confidence we can have in the findings.

Few studies shared the same type of school performance or thinking skills. Only three studies reported the same outcome. None of the studies reported on additional educational support needs and harmful events. We found that, compared with usual routine, physical activity interventions can lead to small improvements in problem-solving skills. This finding was based on high-quality evidence. Moderate-quality findings showed that physical activity interventions do not improve mathematics and reading achievement in children with obesity. Very low-quality evidence also suggested no benefits of physical activity interventions for improving uncontrolled behavioural responses. General school achievement was not reported in studies comparing physical activity interventions with standard practice.

Studies that compared physical activity interventions plus healthy lifestyle education with standard practice were of low to very low quality. They showed no improvement in school achievement or uncontrolled behavioural responses in the intervention group compared to the control group. Problem-solving skills were not reported in studies comparing physical activity plus healthy lifestyle education with standard practice.

Our findings indicate that changing knowledge about nutrition, and changing the food offered in schools can lead to moderate improvements in general school achievement of teenagers with obesity, when compared to standard school practice. Replacing packed school lunch with a nutrient-rich diet plus nutrition education did not improve mathematics and reading achievement of children with obesity. However, the quality of evidence for general school achievement, mathematics and reading was low. This means that future research is very likely to change the results, because included studies showed some methodological weaknesses (for example, small numbers of children and a high dropout of children from studies). Problem-solving skills and uncontrolled behavioural responses were not reported for dietary intervention studies.

How up-to-date is this review?

The review authors searched the scientific literature for relevant studies in February 2017.