Weight Loss- 18 Pounds

I saw Dr. Palo for steroid shots for my knees.  I have not weighed myself on a doctor's scale until today.  I started trying to loose the 17 pounds the dietitian wanted me to lose.  It is almost 5 weeks and I have lost 18 pounds.  I have not stuck to plan for several of those days (Hello birthday), but when I did eat more than the 800 calorie daily allotment I have set (based on what I will be eating post op), I did make the choice not to eat all of my meal and save some for another meal (except birthday cake and I only had 1 piece).  I think that is a victory for me.  Better choices and I am head of schedule for pre-op loss.  I am able to weigh on my home scale now and the scale was off a pound or 2.  I need to find out by how much or is it the difference between barefoot and shoes on.