Ambient heat and nutritional status: a research review

Abstract

The effects of high ambient temperatures and heatwaves on health outcomes are well established, yet their impact on nutritional status remains poorly understood. This systematic review and meta-analysis aimed to synthesize current evidence on the association between elevated temperatures and anthropometric indicators in the general population. The protocol was registered in PROSPERO (CRD42024555573), and a systematic search of electronic databases was conducted in September 2025 using terms related to “high temperatures,” “heatwaves,” and “anthropometric indicators.” Twenty studies were included, comprising 2,943,695 participants, predominantly children under five years of age, mainly from Sub-Saharan Africa. Studies demonstrated methodological heterogeneity, with mixed findings for height-for-age (HAZ) and weight-for-age (WAZ), but generally indicated an inverse relationship between high temperatures and anthropometric outcomes. In adults, elevated temperatures were associated with both underweight and obesity, highlighting complex effects on nutritional status. Meta-analyses in children revealed reductions of 0.12 SD in Weight-for-Height Z-scores and 0.03 SD in HAZ per 1°C increase in average temperature. While effect sizes at the individual level appear to be modest, the population-level implications could be considerable given the widespread and increasing exposure to heat. These findings suggest a potential link between thermal stress and nutritional status, underscoring the need for longitudinal and geographically diverse studies to further clarify causal pathways, identify vulnerable groups, and inform evidence-based climate-adaptive public health strategies aimed at mitigating the potential nutritional consequences of rising temperatures.

Introduction

Malnutrition, which encompasses both undernutrition (underweight, wasting, stunting, and weight loss) and overnutrition (overweight and obesity), poses a significant challenge to the health of individuals and populations. It creates a heavy burden for healthcare systems and adversely impacts economic productivity. [1]. The human and socioeconomic costs of malnutrition are enormous, disproportionately affecting the poorest, particularly women, children, and the elderly. The harmful effects of malnutrition can impact an individual’s health throughout their life, beginning early and persisting into old age. It affects physical, mental, and social well-being, while also increasing the risks of morbidity and mortality [2,3].

Emerging research on climate and health suggests a link between high temperatures and malnutrition [2,4,5]. The pathways via which high temperatures impact health and nutrition are complex, involving short-, medium-, and long-term mechanisms, and may vary by geography, socioeconomic context, and ecosystem [6]. Children are particularly vulnerable to the harmful effects of extreme heat due to their developing thermoregulatory systems, which are less efficient than those of adults [7]. This vulnerability is further exacerbated by prolonged outdoor exposure during play and the environmental conditions of households situated in agricultural regions, where extreme heat may be more intense and shelter less accessible. Heat stress can cause a series of acute health problems, including loss of appetite, poor nutrient retention, and increased diarrhoea and dehydration, hence leading to poor nutrient and calorie absorption and ultimately weight loss [8].