Minor weight loss

Patient: Thanks for your upcoming answer…i am a healthy 66 yr old male…just had a partial knee replacement 2 week ago…am performing multiple PT exercises 3x day…my weight is normally around 188lbs…before surgery, i noticed that after weighing prior to bed, i was in the normal range…first thing in the morning, my weight would be around 4 lbs less…??…is that normal…now, after surgery, i’ve dropped around 6 lbs…??…my eating habits are returning to normal..however i was not overly hungary for two to three days, following surgery…should i worry about this, or give it a couple more weeks…thanks

Doctor: