Obesity is now called a global epidemic because its prevalence and severity are increasing worldwide at alarming rates, both in adults and in children. The increase in obesity is most marked in affluent parts of the world, including Europe where obesity has become the predominant nutritional disorder in childhood and a major public health problem.
Obese children tend to become obese adults, and they carry a high risk of acute and chronic diseases, reduced life expectancy, and lower income. Treatment and prevention of childhood obesity have been identified as priorities in Europe. However, obesity treatment is costly. The long-term efficacy of established therapeutic options is limited even with intensive efforts, and cost-benefit-ratios of usual therapies are quite unsatisfactory. Therefore, the development of effective strategies for primary prevention is particularly attractive.
Early prevention is important because childhood obesity has severe short and medium term consequences in childhood and adolescence, as well as long-term effects that extend well into adulthood. Obese children tend to experience severe psychosocial distress and considerable discrimination. When they reach adulthood they achieve lower rates of completed advanced education, lower incomes and fewer stable partnerships.
Medical complications of obesity during childhood and adolescence include untoward effects on the cardiovascular risk factors dyslipidaemia, arterial hypertension antioxidant vitamin status, and glucose intolerance. Obesity plays a key role in the increase of non-insulin dependant diabetes mellitus that occurs in adolescence. Persistence of childhood obesity into adulthood is common and associated with markedly increased morbidity and mortality, and high costs to the society.
An individual's obesity risk depends on genetic predisposition and current lifestyle, in particular the level of physical activity and dietary choices. Nutritional factors during early life may modulate later obesity risk, a phenomenon called metabolic programming or metabolic imprinting. Animal studies have shown that dietary manipulation in the perinatal period, in particular an alteration of protein intake, have lasting effects on body weight in adult animals. Studies in humans suggested that maternal undernutrition during the last trimester of pregnancy or the first months of life is associated with significantly less obesity in their children at young adulthood.
Postnatal infant feeding also modulates the later risk of obesity and of being
overweight. Infants fed formula are more likely to become obese than breastfed
infants. A clear dose-response effect has been identified, with a longer
duration of breast feeding having a more marked effect on reducing later obesity
risk. Thus, in industrialized countries the promotion of breast feeding may help
to decrease obesity prevalence in childhood. The underlying mechanisms of this
effect remain to be elucidated. The higher protein content of infant formulae,
compared with breast milk, could be a causal factor.