Small Weight Gain During Recovery Phase of Abdominoplasty

As long as you have good eating habits, your weight gain should only be temporary due mostly to fluid retention. It is important during the healing stage, not to deprive your body of much needed nutrients. Within 6 weeks of your surgery, you should be able to get back to your regular exercise program

I would not recommend starving yourself while you are healing.  It is normal for some weight gain after surgery, it is just going to take time.  Once you are given the OK and can start exercising you will loose the weight. 

A brief and temporary weight gain of 5-10 pounds is very normal during the recovery period following a tummy tuck. To some degree this is due to retained fluids. Within 3 weeks you should be able to return to light activities and by 6 weeks more strenuous.