This article by Live Science talks about the fact that some babies at 9 months old are already obese.
Given the fact that formula is empty calories, it’s no wonder
Breast milk is the only food babies should be given for at least 6 months-year (better if it’s longer). It changes and reformulates to baby’s growing needs, gives immunity, has live antibodies and even makes for smarter children later in life.
Another supporting article: