Hydro-climatic anomalies and livelihoods associated with thinness among children and adolescents in Mount Meru,...

School-aged children and adolescents face significant nutritional challenges in sub-Saharan Africa yet remain understudied compared to under-five populations. Climate variability increasingly threatens food security in rural communities, but evidence on climate-nutrition relationships beyond early childhood is limited. We investigated associations between hydro-climatic anomalies, livelihood strategies, demographic characteristics, and thinness among school-aged children and adolescents on the slopes and surrounding plains of Mount Meru, northern Tanzania.

We analysed five waves of anthropometric data from 26,009 records of children and adolescents aged 6-18 years attending 18 public primary schools in the Mount Meru ecosystem between 2010 and 2015. Thinness was defined as BMI-for-age Z-score < -2 using the World Health Organisation (WHO) 2007 growth references. Bayesian logistic mixed-effects models were used with school-level and temporal random effects to examine associations of thinness with sex, age, dominant livelihood (farming, agropastoralism, pastoralism), and standardized anomalies in precipitation, evapotranspiration, and land-surface temperature.

Overall thinness prevalence ranged from 61.2% in 2010 to 72.7% in 2015. Girls had lower odds of undernutrition than boys (odds ratio [OR]: 0.58, 95% credible interval [CrI]: 0.54-0.61), but age-sex interactions revealed complex developmental patterns. Girls showed peak vulnerability at age 12 years followed by sharp decline, while boys demonstrated more sustained risk through mid-adolescence. Children and adolescents from pastoralist communities had substantially higher undernutrition odds compared to farming communities (OR: 2.21, 95%CrI: 1.31-3.50). Above-normal precipitation was protective (OR: 0.34, 95% CrI: 0.20-0.54), while elevated evapotranspiration increased the odds of thinness (OR: 2.18, 95%CrI: 1.41-3.24).

The odds of thinness among school-age children and adolescents vary substantially by livelihood strategy and respond dynamically to hydro-climatic anomalies. Age- and sex-specific vulnerability patterns reveal critical windows requiring targeted interventions. Evapotranspiration emerged as a particularly informative climate indicator for nutritional surveillance. These findings support integrating climate monitoring into school-based nutrition programs and developing livelihood-specific adaptation strategies for climate-vulnerable communities.