Babies who were exclusively breast-fed for three to five months were a third less likely to be obese by the time they started school than those who were bottle-fed, according to the study. Since obesity in childhood is linked with obesity in adulthood, the researchers say the finding may help in the long-term prevention of fatness.
The study, of 9,300 children in Bavaria, Germany, showed that the longer babies were breast-fed the smaller their chance of becoming fat later on. The figures apply to babies exclusively breast-fed, with no supplements of bottle milk or solid food.
Breast-feeding is known to be superior to bottle-feeding because it provides the right nutrients for the developing baby. The researchers, from the Institute for Social Paediatrics at Ludwig Maximilians University, Munich, say in today's edition of the British Medical Journal that the protective effect of breast-feeding from obesity is more likely to be related to the composition of breast milk than the lifestyle associated with breast- feeding.
They add that other research shows bottle-fed babies have higher levels of insulin in their blood, which stimulates the deposition of fat. Breast milk contains substances which inhibit the production of fat cells and breast-fed babies consume fewer calories and less protein. A high intake of protein early in life may increase the risk of obesity later, they say.
Obesity has more than doubled in the UK during the last two decades.