A one‐year school‐based diet/exercise intervention improves non‐traditional disease biomarkers in Mexican‐American children

School‐based interventions are an effective way to treat childhood obesity. The purpose of the present study was to biologically validate an established school‐based intervention designed to reduce standardised body mass index (zBMI) over a period of 12 months. This intervention focused on a subset of Mexican‐American children who were participating in a larger clinical weight loss study. Plasma samples were analysed from self‐identified Mexican‐American children (12–14 years) who were randomised to either a school‐based intervention (IN, n = 152) or self‐help control (CN, n = 69). Treatment was 4 days week^?1 of exercise (45 min day^?1) and 1 day week^?1 of nutritional counselling for 6 months. Fasting (>8 h) blood samples were collected at baseline, 6 months (end of active intervention) and 12 months (6 months after the end of the active intervention). Plasma resistin, adiponectin and leptin concentration were measured using a multiplex assay. Separate linear mixed models and a P < 0.05 were used to test for significance. Significant group × time interactions were found for resistin (P < 0.0001), adiponectin (P = 0.001) and leptin (P = 0.013). For resistin, IN was 12% lower at 6 months than CN. Adiponectin concentration in IN was greater at 6 months (26%) and 12 months (8%) than CN. Leptin concentration was 22% lower for IN at 12 months than CN. We have previously reported that our school‐based intervention reduced zBMI and now reported alterations in biologically relevant disease biomarkers. Some of the observed changes were only present at the end of the active intervention (resistin), while others persisted until 12 months (leptin and adiponectin). These changes underscore the effectiveness of our school‐based intervention at not only improving zBMI but also at reducing disease risk.