We aren't used to breastfed babies and often moms will compare breastfed babies with formula fed babies who typically eat every 3 or 4 hours. (newbabynewpaltz.com)
Many of those growth charts are based on the weights of formula fed babies who gain much more rapidly than breastfed babies for a variety of reasons. (mommyedition.com)
Typically it is said to start solids as early as 4 months for formula fed babies because they need the extra nutrition, but it's different for breastfed babies. (babyledweaning.com)