Weaning practices and later obesity

Many studies correlate the nutrition of the first one thousand days of life to the development of non-communicable diseases, in particular to the development of obesity. A high intake of protein in the first 2 years of age, leading to an increased production of the insulin-like growth factor 1 (IGF-1), is an example of programming in obesity development. The role of nutrients in promoting obesity development in later ages has to be approached in terms of both quantity and quality. Infants living in developed countries face a notable increase in protein intake when starting a complementary feeding (CF): the first study showing a correlation between protein intake in infancy and obesity in later age was published 20 years ago. High intake of protein from milk and dairy products origin only are likely to be associated with an increased fat mass at different ages, whereas protein of meat and vegetables origin does not seem to play a significant role. The relationship between fat during CF period and obesity development is even more controversial, while no data is available, yet, about the role of fat quality. As for carbohydrates, little is known on their role during the first two years of life in relation to the development of obesity, even though the association between simple sugar and obesity development has been extensively studied. But the influence of CF in favouring obesity development is not restricted to the effects of nutritional and metabolic factors: During the first year of life infants shift from consuming milk only to a wide range of foods with different flavours, textures, and taste. Infants tend to like sweet and salty tastes and to dislike sour and acid ones. During the CF time, a scarce variety of foods and a specific monotonous model of taste development can lead to eating pattern predisposing to unhealthy foods preferences, which in turn will contribute to obesity development.