Background: This study is a longitudinal analysis of how the transition of a mother, father, or any other family member to obesity affects the likelihood of children 5–12 years of age becoming adolescents with overweight or obesity during the 7–10-year period between 2002 and the period from 2009 to 2012 in Mexico. Methods: The study used two rounds of the Mexican Family Life Survey, a multipurpose random national survey that collected information on 8441 households, including 38,233 individuals in 2002 and successfully followed up with 3202 children until the period from 2009 to 2012. We used logistic regressions to calculate how family characteristics related to the evolution of body mass indexes among children, controlling for individual, family weight-related characteristics, and the socioeconomic level of the family. Results: The transition of any family member toward obesity is more relevant in determining the transition to obesity among normal-weight children than socioeconomic level of the family and individual characteristics, such as sex, schooling, and occupation. Conclusions: The transition of any family member toward obesity is associated with the transition to obesity among normal-weight children. A family-based approach to obesity prevention has yet to be incorporated into national policies.

Objective. To estimate to what extent the parental tran­sition to obesity affects the likelihood that normal-weight teenagers also transition to obesity. We depart from the hypothesis that the transition to obesity specifically among parents is the main factor affecting the development of obesity during adolescence. Materials and methods. Using two rounds of the longitudinal Mexican Family Life Survey (MxFLS) and logistic regressions, we investigated how family weight-related characteristics affected the likelihood of teenagers 13 to 18 years of age in 2002 of becoming affected by obesity after seven to ten years. Results. The results confirm that if any of the parents were affected by obesity during the teenage period, the adolescent is more likely to become affected by obesity. Conclusions. Results confirm that, different from childhood obesity, the transition of parents to obesity during the adolescence of teenagers is the most important family factor affecting such transition.