This study examines the effectiveness of school-based nutrition education programmes in preventing obesity among primary school children in Western African countries, with a focus on South Africa. Nutrition education programmes were implemented in 10 randomly selected primary schools across South Africa, with a control group of 5 schools not receiving the intervention. Data collection included pre- and post-programme surveys to measure health literacy and dietary changes. A significant improvement (p < 0.05) was observed in students' knowledge scores related to nutrition education after the programme (mean increase from 42% to 68%). The school-based nutrition education programmes demonstrated a positive impact on health literacy and obesity prevention. Further research should be conducted to evaluate long-term effects of these programmes, with potential expansion to other regions in Africa. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.