HI I did a read through on all the other responses before I decided to answer. The answer is anywhere b/w 2 and 2 and half. WHY: Tbe brain is still developing and needs the "fat" from the milk to aid in this natural process, Regardless of the weight. Also, this to reinforce the growth on bone tissues which at this age is shaky among most toddlers. I use this as an advantage since as your child gets older....into the young teens, old teens, they withdraw from all these "nutrients" from milk, etc. and rely on sugary drinks and water because it's "cool". I have young children and have had my experience as a teacher to see the transition.
I wouldn't be in any rush to switch over, she'll grow in time and develop beautifully, no matter the weight! I only say this because I am a small/med. framed gal and my husband is a big guy 6 ft. 2++ something lbs and as babies...they were overtly "big" babies. Now that they are a bit older, it has all evened out and they are in the "normal percentile".
SO- again, when others talk about health reason, it's the body still growing and developing a process you definately do not want to rush. :-)!
Mom of 4.
Mom of 4(yes its a crazy life but it's my life)