Babies raised on formula feed are twice as likely to be obese at five-six years of age than breast-fed babies, say Ridiger von Kries, paediatrician and epidemiologist at Ludwig Maximilians University in Munich, Germany, and his team. They conducted a survey among more than 9,000 Bavarian school children and found that the longer a baby was breast-fed, the greater protection it had against becoming overweight. Babies breast-fed for two months or less were almost four times as likely to be obese as those breast-fed for more than a year. Scientists say that the link has been anticipated in the past but the findings provide definite proof for it. According to von Kries, the weight gap could be caused by a number of reasons. Mothers' milk has been shown to contain factors that inhibit the production of chemicals associated with fat deposits ( British Medical Journal , Vol 319, No 7203).