A systematic review identified 11 eligible studies of school-based diet and physical activity interventions among African children and adolescents, from 2000 to 2025. Nearly three-quarters were conducted in South Africa, 70% were quasi-experimental rather than randomised, and most were delivered in primary schools as multi-component programmes.
Individual studies reported modest improvements in adiposity and in maintaining normal weight. Pooled across nine intervention comparisons, the effect on BMI-for-age was a mean difference of 0.03 with an interval from -0.24 to 0.29 — no effect, with substantial heterogeneity at I² of 69%. Combined nutrition and activity interventions showed reductions in a few comparisons.
The geography is the finding as much as the effect. Eleven studies across an entire continent, three-quarters from one country, mostly without randomisation, is a thin evidence base for a population where obesity is rising fastest. The honest conclusion is not that school programmes do not work, but that we do not know, and that the studies capable of answering have largely not been done outside South Africa.
- Eleven studies for a continent, 73% of them from South Africa
- 70% quasi-experimental, so allocation was not random in most
- Pooled BMI-for-age difference of 0.03 — an effect of essentially zero
- Individual studies reported improvement; pooling did not sustain it
- Reads as an evidence gap rather than as evidence of no effect
The statistics, in plain English
A mean difference of 0.03 with an interval from -0.24 to 0.29 is a null result centred almost exactly on no effect. But with I² at 69% the studies disagree substantially, and with most being quasi-experimental the pooled estimate inherits their confounding. This is better read as absence of evidence than as evidence of absence.
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