Background and objective Several early life determinants play a role in childhood obesity. Rapid weight gain and overweight in infancy increases the risk while breast feeding seems to protect against childhood overweight. However, should we worry about exclusively breastfed overweight infants? The aim of the study is to examine the association of feeding type (exclusive breast feeding (EBF), formula feeding or mixed feeding) and overweight at the age of 6 months with the risk of overweight at the age of 5–6 years.

Methods The Amsterdam Born Children and their Development study is a large prospective population-based birth cohort study conducted in Amsterdam, the Netherlands. Children with complete information pertaining to feeding type and weight status at the age of 6 months and 5–6 years were included (N=3367). EBF was defined as receiving only breast feeding for at least 3 months. Overweight at the ages of 6 months and 5–6 years were defined by the WHO child growth standards and the International Obesity Task Force guidelines, respectively. The association of feeding type and overweight at 6 months with overweight at 5–6 years was assessed using logistic regression analyses.

Results Overweight infants have a 4.10-fold (95% CI 2.91 to 5.78) higher odds of childhood overweight compared with those who were not overweight, independent of feeding type. EBF did not affect the association between infant overweight and childhood overweight.

Conclusions Overweight in infancy increases the odds of childhood overweight, equally for exclusively breastfed and formula fed infants. Overweight prevention should start before or at birth and applies to formula fed children as well as exclusively breastfed children.