Introduction The parallel rise in prevalence of asthma and overweight/obesity in some Latin American countries has led to suggestions of a link between the two epidemics. The aim of this study was to explore the effects of being overweight on wheeze, exercise-induced bronchospasm and atopy.

Methods A case-control study was conducted among 809 Afro-Ecuadorian children aged 7–19 yrs living in rural communities in tropical Ecuador. Asthma cases were selected based on the presence of recent wheeze and controls as a random sample of those without symptoms by questionnaire. Atopy was measured either by the presence of allergen specific IgE (asIgE) in serum or by allergen skin test reactivity (SPT). Overweight children were those with a Body Mass Index (BMI) ≥ +1 z-score based on WHO growth curves (2007).

Results Comparing atopic vs non-atopic children, the prevalence of SPT (adj. OR 2.12, 95% CI 1.22 to 3.68) and the presence of asIgE (adj. OR 2.30, 95% CI 1.10 to 4.83) was greater in overweight children compared to those with normal weight/underweight. Comparing non-atopic wheezers with non-atopic non-wheezers, being overweight was significantly associated with non-atopic wheeze (adj. OR 2.22, 95% CI 1.07 to 4.63) when atopy was defined as asIgE but not SPT. Being overweight was not significantly associated with atopic wheeze (comparing atopic wheezers with atopic non-wheezers) and with severe wheeze or exercise-induced bronchospasm irrespective of atopic status.

Conclusion Although being overweight was associated with atopy, it was also associated with wheeze, and somewhat surprisingly this latter effect was not observed among atopic children.