Childhood obesity has increased dramatically over the last decades, representing one of the most serious public health hazards of the 21st century. Efforts must be made by healthcare professionals to prevent it, as it is associated with short- and long-term risks for physical and mental health and because of the increased possibility to persist during adulthood. From antiquity human breast milk was considered the ideal nourishment for the newborn. Breastfeeding is beneficial for the mother-child dyad. Among others, existing data suggest that it reduces the risk for childhood and adolescence obesity. The mechanisms for this are numerous and include the feeding behavior breastfeeding infants acquire, their growth rate, the ‘early protein hypothesis’, the role of leptin that is found in increased levels in human milk, the dietary choices the breastfed infants make during childhood and adolescence and finally the differences in their bowel flora. Meta-analyses provide sufficient evidence for this protective effect, with a dose-response effect as to the duration of breastfeeding. Healthcare professionals involved in the care of the mother-infant dyad must encourage and support mothers to breastfeed their infants for a long period of time, if obesity were to be prevented. Aim of this review is to provide an account of existing data on the association of breastfeeding and the reduced risk of obesity in childhood and adulthood.