I am not sure I understand 'faster than optimum"??? Need more information. Is his weight loss going to below the chosen weight? How far over when he started? Lots of variables here. If the work is right and the dog is healthy, adjust his food accordingly. If there is a lot of work going on 3% is normally not a lot. Check what you are feeding and then maybe check the dog. Not sure any of this helps but there are lots of variables. EWO