G E N E R A L I N T R O D U C T I O N Adipose tissue expanding in the obese state synthesizes and secretes metabolites and signaling proteins like leptin, adiponectin, and tumor necrosis factor-‐alpha. These factors are known to alter insulin secretion and sensitivity and even cause insulin resistance8. The most important consequences of insulin resistance in chil-‐ dren include increased incidence of type 2 diabetes, atherogenic dyslipidemia and arterial hypertension, which lead to increased cardiovascular risk. In case of female pediatric patients a higher incidence of polycystic ovary syndrome (PCOS) is ob-‐ served9. Besides, there are numerous medical comorbidities associated with obesi-‐ ty in childhood. Nonalcoholic fatty liver disease (NAFLD) is increasingly prevalent in pediatric age individuals, in parallel with increasing obesity, and can lead to liver inflammation, fibrosis and even cirrhosis10. Not only severe physical consequences of obesity can be seen, but also psychosocial problems are obvious like stigmatization and discrimination11. Obese children have more problems with playing sports with their peers and may suffer from bullying12. They may also develop a low self-‐esteem and a poor body image. It is generally agreed that being obese, or even being overweight, is a highly stigmatized condi-‐ tion. There is a considerable discussion in the literature on the stigma of obesity and the way that obese people are treated in western society, from childhood teas-‐ ing and bullying13, avoidance by others14, and misplaced humour15. Obese children are at risk to become isolated, miss the connection with peers and may drop out of society. There are a couple of predictive risk factors to develop obesity. In general, children with a BMI ≥ 95th percentile have a high risk for adult obesity16. Also an early age of adiposity rebound (the moment of increase of the BMI) is an important predictor for obesity in adolesence17. Exposure to maternal obesity, with or without gesta-‐ tional diabetes, having a high birth weight18, but also low birth weight, together with catch-‐up growth, is associated with a significant risk of adult obesity. Studies including randomized controlled trials consistently show that higher protein intake during infancy is associated with the development of obesity. Lack of breastfeeding was also associated with obesity in many observational studies19. The hypothesis that breastfeeding could have a protective effect against obesity is supported by epidemiological evidence, but literature data are still controversial. If this hypothe-‐ sis is confirmed, it will represent one more advantage of breastfeeding, as well as a new "weapon" to fight obesity. The potentially implicated mechanisms still have to be clarified. Breastfeeding involves several aspects, such as the amount of food intake, composition of the food, time of introduction of solid foods and develop-‐ ment of regulatory eating mechanisms. Also behavioral aspects related to the mother-‐child relationship and formations of eating habits are important aspects of breastfeeding20. 13
Proefschrift binnenwerk Manon Ernst_DEF.indd
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