Gordura abdominal subcutânea e visceral aos 30 anos : caracterização e determinantes, coortes de nascimentos de 1982, Pelotas, Brasil

Abstract

Central fat accumulation, and in particular intra-abdominal or visceral fat depots, has been identified as an independent risk factor for insulin resistance, cardiovascular diseases and hypertension. In 2012-13, all members of the 1982 Pelotas (birth) cohort study were sought and 3,701 subjects were examined. The follow up rate was 68%. Valid data on visceral (VFT) and subcutaneous abdominal fat (SAFT) thicknesses were obtained by ultrasound from 3,493 participants (1,724 men and 1,769 women) aged 29-31y. The present thesis comprises three scientific publications. Firstly, we studied the associations between genomic ancestry, socioeconomic position and abdominal fat depots. Use of genomic ancestry markers in this uniquely admixed population allowed separate investigation of independent genetic and social influences. African ancestry was associated with lower visceral and subcutaneous abdominal adiposity, particularly in men, while higher educational level was associated with lower visceral fat in men and women, but not with subcutaneous fat. Secondly, we performed a systematic literature review on the associations between birth size and abdominal adiposity in adults, while also investigating the role of adjustment for body mass index (BMI). Birth weight tends to be associated with larger adult size in general, including both waist and hip circumferences. The substantial changes in coefficients after adjustment for adult BMI suggests that post-natal growth strongly affects relative central adiposity, whereas BW per se does not play a role. Finally, we investigated the effects of birth weight, linear growth, and relative weight gain from birth to adulthood on VFT and SAFT at age 30y. Both VFT and SAFT showed positive associations with weight and conditional relative weight gain in both men and women, VFT at all ages from 2y and SAFT at all ages from birth. In women, height in infancy was inversely related to VFT but positively related to SAFT. In men, height was not related to either outcome. In men and women, stunting at age 2y appeared to limit the accumulation of SAFT but not VFT. Women born with intrauterine growth restriction (IUGR) had greater VFT and a stronger positive influence of infant weight gain 0-2y on VFT than non-IUGR women. In terms of policy implications, our findings reinforce the advantages of being born with an appropriate birth weight, and the hazards of rapid postnatal gains in weight relative to linear growth, particularly after the critical window of the first 1,000 days.