Public Health Nutrition: 14(7), 1237–1244 doi:10.1017/S1368980010003009 Childhood underweight, weight gain during childhood to adolescence/young adulthood and incidence of adult metabolic syndrome in the SUN (Seguimiento Universidad de Navarra) Project Adriano M Pimenta 1 , Juan-Jose ´ Beunza 2 , Almudena Sanchez-Villegas 3 , Maira Bes-Rastrollo 2 and Miguel A Martinez-Gonzalez 2, * 1 Department of Maternal and Child Nursing and Public Health, Nursing School, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil: 2 Department of Preventive Medicine and Public Health, Medical School & Clinic, University of Navarra, Irunlarrea 1, CP 31080, Pamplona, Navarra, Spain: 3 Department of Clinical Sciences, University of Las Palmas de Gran Canaria, Las Palmas de Gran Canaria, Spain Submitted 1 May 2010: Accepted 22 September 2010: First published online 17 November 2010 Abstract Objective: To assess associations between childhood body weight, weight gain during childhood to adolescence/young adulthood and incidence of adult metabolic syndrome (MetS). Design: A dynamic prospective cohort study (the SUN Project; Seguimiento Universidad de Navarra). Participants were asked to select which of nine body images most closely represented their body shape at ages 5 and 20 years, and it was used as a proxy of BMI. An incident case of MetS was diagnosed according to criteria of the International Diabetes Federation. Associations between childhood body weight, weight gain during childhood to adolescence/young adulthood and incidence of adult MetS were estimated by multiple-adjusted odds ratios and their 95 % confidence intervals. Setting: University of Navarra, Spain. Subjects: The study included 5317 university graduates, followed-up for a median of 6?1 years. Results: The incidence of MetS was 2?9% (1?7 % in women and 5?1 % in men). Among men, body shape at age 5 years was inversely related to adult MetS (OR 5 0?83, 95% CI 0?72, 0?97), whereas weight gain during childhood to ado- lescence/young adulthood was directly associated with adult MetS (OR 5 1?49, 95 % CI 1?01, 2?18); both childhood underweight (OR 5 5?20, 95 % CI 1?87, 14?50) and childhood obesity (OR 5 4?66, 95% CI 1?40, 15?51) increased the likelihood of adult MetS. No association was apparent among women. Conclusions: These results support treating childhood underweight and weight gain during childhood to adolescence/young adulthood as part of comprehensive adult MetS prevention efforts in men. Keywords Body image Body weight changes Child Metabolic syndrome Metabolic syndrome (MetS) is characterized by the clustering of cardiovascular risk factors such as obesity, dyslipidaemia, insulin resistance, hyperinsulinaemia, glucose intolerance and hypertension (1) . This syndrome is recog- nized as an important public health concern worldwide, owing to its prevalence of over 20 % in adult populations around the world (1–4) and also to its strong association with CVD and type 2 diabetes, both main causes of death on a global scale (1,5,6) . In general, there are differences in the prevalence of MetS and its components among men and women. MetS has been more frequent in men than in women, but the prevalence has risen particularly in young women, where it is mainly driven by obesity. Furthermore, the presence of impaired glucose tolerance is higher among women, whereas the other MetS components are more common among men until women enter the menopause period (7) . Some studies have also consistently shown high rates of MetS in people who were born small, because insulin resistance, which is recognized as a key element of this syndrome (8) , could be a genetically ‘programmed’ response to fetal undernutrition (9) . However, this hypothesis has been criticized for the reason that the prevalence of underweight newborn children is decreasing whereas the *Corresponding author: Email mamartinez@unav.es r The Authors 2010