Weight loss days VERSES work out days (?)

It's not a bad thing, it's just that I don't understand it, I'm wondering if someone can give me ideas as to why. 

I am a 55 yr old woman.  Severe arthritis, and had a bad fall last year previous to VSG.  Was walking with a cane until just about a month ago.  Now only use it in crowds or if I'm really tired, and it's late in the day.  I take anti-inflamatories for the joint issues.

I started "working out" at Curves several months ago, and doing physical therapy.  I could only do the "top half" exercises at Cruves per my doc and PT. But I was moving, and increasing my range of motiion.  NO walking.  As I have lost weight, I am able to move more.  As my PT (and time) has healed my muscle tear and torn connective tissues....I am able to do more. 

The last three weeks I can actually do about 80% of the work out; and am getting a 'workout' at Curves.  I'm going 3x a week.  On days I don't go I try to get a short walk in.  I am allowed to walk for up to 15 minutes a day. 

During the week, when I'm doing curves I don't seem to lose much if any weight at all.  But on the weekends, when I either don't do anything, or just take the pup for walk, I drop the weight.  I am not complaining, I just would like to understand why this happens.  Any clues ?

PS -- I'm almost at 90 pounds lost !!!  Can you believe them apples ???!!! 
 

I would probably think that you are building muscle and burning fat but Muscle weighs more. Have curves track your BMI they have a machine that  can give you your muscle/fat ratio and measure your inches.
I bet that will brighten your day.

You are likely not adding muscle that fast to effect your weight like that- it takes weeks of hard lifting to really up the numbers, it doesn't happen in a day or two.. but what you are likely doing is - when we work out, we burn energy stored in the muscles and they pull in water to heal the little tears and inflammations we cause and to rebuild the energy stores.. So, basically- you are likely holding onto a bit of water post-workouts.

Jo777 THAT makes sense. I was just trying to make some sense out of it all. Not that it matters much to me, as long as the general trend on the scale is downward !!