Factors that modulate catch up growth influence the quantity) and quality of the recovered tissue. Insulin and IGF-1 respond to dietary changes in carbohydrates and proteins; evidence shows that IGF-1 and leptin may be good indicators of nutritional recovery. The optimal diet to promote catch up growth is still controversial. There is consensus on the need to adjust the energy-protein intake to the growth velocity observed, without encouraging excessive eating, to avoid obesity. Zinc supplementation and physical activity appear as relevant factors to promote the synthesis of lean mass. In some models of early malnutrition, a better catch up growth during childhood, is associated with a higher frequency of chronic diseases and mortality in adulthood. In this context, we will review some factors that seem relevant to the modulation of catch up growth, which should be taken into account when reviewing the therapeutic guidelines to treat malnourished children (Rev Med Chile 2003; 131: 213-9).