Why do i throw up while on diet?

i think its maybe because you were eating such low calorie stuff and then all of a sudden you ate/drank the heavy stuff and you werent used to it right away.. ? By the way 125 lbs at 5'3 is fine.. if you want to look better just work out.. run/lift/eat and i guarantee you'd look even better than just losing 15 pounds straight by eating those small planned out meals