If my pet is overweight, how much weight should he lose and how quickly should he lose it?
In general, a good goal would be to have your pet lose 0.5-2.0% of its body weight per week. For instance, a 50-pound dog should lose 1/4 to 1 pound per week. A weight loss of 2% or more per week can cause more harm than good. It is especially important that obese cats do not lose weight too rapidly.