Quoting MommyToWesley:" If you're having problems now with constipation, introducing whole milk and weaning off formula is only going to make it a lot worse. It is so much harder for babies to digest."
Not always. Formula constipated my dd so bad it was horrible. I put her on whole milk at 9 months old and she was completely weaned off at 11 months old (formula) and she was so much better then she was on the formula. She still gets constipated every now and again, but she she has medical issues with her bowels, but yeah formula was the worse, whole milk was 100% better for her constipation.