This article estimates the effect of international migration from Mexico to the United States on the obesity status of children who remain in Mexico. Theory suggests that increased liquidity as well as changing time allocations resulting from migration may influence obesity outcomes. Natural disasters are used as an identification strategy. Results suggest that older boys in urban areas are more likely to become obese when either a male or female migrates from the household, while girls in urban areas are less likely to become obese. Both changes in food expenditure patterns and time use changes after migration are likely pathways that affect childhood obesity. While there are some changes in food expenditures, we find more importantly that urban girls engage in more housework and screen time after migration, whereas urban teen boys do not substitute for adult work as much as girls. These changes in strenuous activities, particularly for girls, likely explain the differential effect that migration has on boys’ and girls’ obesity outcomes in Mexico.