Background As most obese adults were not overweight as children, the prediction of adult obesity from childhood body size alone is limited. We constructed a two-way, multifactor risk assessment framework for predicting adult obesity during childhood using the Foresight Obesity System Map and tested it against longitudinal data from the 1958 National Child Development Study.

Methods The framework divided study participants according to two categories of risk: ‘conditioning factors’ (past/fixed events and conditions) and ‘intervention factors’ (present and modifiable). At the age of 11 years, conditioning factors were ‘low/high birth weight’ and ‘absence of breastfeeding’, and intervention factors were ‘low childhood activity level’ and ‘having at least one obese parent’. From a composite score of all four variables, study participants were assigned to one of the four risk groups: low risk, past ‘conditioning’ risk only, present ‘intervention’ risk only and high combined risk. ORs and relative risks for the development of future overweight/obesity at ages 23, 33 and 42 years were calculated for each risk group.

Results Those identified in the highest risk category at the age of 11 were around twice as likely to become overweight (body mass index (BMI)≥25 kg/m²) by the age of 23 years, and obese (BMI≥30 kg/m²) by ages 33 and 42 years, in comparison to their low-risk peers (total sample, N=11 752). Increased prevalence of future obesity was also observed for high-risk children who were not already overweight at the age of 11 (filtered sample, N=9549).

Conclusions This framework identifies a greater proportion of the population that is at risk for future obesity than does childhood weight assessment alone.