Assessing the effectiveness of healthy weight interventions in the early years of childhood: a systematic review and meta-analysis of evidence from high-income countries.

backgroundEarly childhood represents an important opportunity for establishing lifelong health behaviours, including the maintenance of a healthy weight. Given that weight patterns established in early life often persist into adolescence and adulthood, there is an urgent need to understand whether universal interventions in early childhood are effective in preventing excess weight gain. We aimed to systematically synthesise the effects of universal healthy weight interventions for pre-school children on anthropometric outcomes.

methodsWe searched nine academic databases and included studies published from 2011 with pre-post implementation assessments of anthropometric outcomes amongst preschool children aged 5 years and under. Eligible studies included interventions that incorporated diet, physical activity, and/or behavioural change components. All studies were included in a narrative synthesis and, where possible, three-level random-effects meta-analyses were conducted to pool standardised mean differences.

resultsA total of 40 studies (n = 26,977 participants) met the inclusion criteria. The most commonly reported outcomes were BMI z-score (zBMI; k [number of studies] = 27), weight status categories (k = 19), BMI (k = 14), BMI percentiles (k = 11), body weight (k = 8), waist circumference (k = 8), skinfolds (k = 6), percentage body fat (k = 3), fat-free mass index (k = 3), and fat mass index (k = 2). The findings from the meta-analyses suggested that children receiving interventions had significantly lower zBMI (SMD [standardised mean difference] = -0.085, 95% CI -0.140, -0.029), lower waist circumference (SMD = -0.186, 95% CI -0.361, -0.011), percentage body fat (SMD = -0.159, 95% CI -0.290, -0.028) and higher fat-free mass index (SMD = 0.170, 95% CI 0.012, 0.328) compared to controls. No significant differences were found for BMI percentile. Narrative synthesis indicated limited evidence of effectiveness.

conclusionsUniversal multicomponent healthy weight interventions for preschool children in high-income countries were associated with modest but meaningful improvements in zBMI, waist circumference, percentage body fat, and fat-free mass index. These findings suggest that early childhood interventions can be effective if delivered at scale and may serve as a key element in broader childhood obesity prevention strategies.