This goes against everything I have read about and prior experience. Maybe this isn't enough data to see a pattern but it certain goes against most working theories. (Not that I am complaining, I am just trying to understand.)

I attempted free weights strength training in Nov/Dec and saw the scale going up the next a.m. after every session and to go down when resting. I got away from it during the holidays.

I did a 1/2 circuit class a few of times but it got cancelled by the gym for lack of attendance. But the scale still showed a bump the next day and then down with rest.

This week I attended their BodyPump class this week on Tues and Thursday. I was expecting the scale to bump up a pound or two on Wednesday and today. But it dropped 2 on Wed and 1 today. I think my weight was up on Tues because I did a 1 hr yoga class and 1 hr water aerobics.

I have been perfectly on plan with food choices and water.

This doesn't make sense. So what's going on?

S: 220 - rest
M: 220 -1 hr yoga, 1 hr WA
T: 221 - 1 hr BP
W: 219 - 1 hr WA
T: 219.5 - 1 hr BP
F: 218.5 - 1 hr WA
S: 216.5
BodyPump - The original barbell class that strengthens your entire body. This 60-minute workout challenges all your major muscle groups by using the best weight-room exercises like squats, presses, lifts and curls.

I do a body pump style class. It doesn't seem to mess with the scale the way heavier weights do. My scale doesn't complain the next day from the class, only when I go to the weight room an lift heavy. I went to the class yesterday (every M,W,F) and was down .6 today.

My understanding of the reason for this phenomenon is that when you work out you create micro-tears in muscle tissue. Part of the healing process is that the muscles hold water. The retained water then results in a small temporary weight gain.

I'm not a professional -- this is just an explanation that I read somewhere for a pattern that I have observed myself.

the water/glycogen thing is true, but I think she's saying she's not having the usual gains.

Maybe your muscles are getting a bit acclimated and therefore need less water/glycogen/time to heal. when I first exercised or when I bump it up a notch more than usual, is when I get that day of gain/soreness/water

Oh gosh, this is because weight loss is not linear. It's true about the muscles retaining water for repairs. You can also retain water due to hormones or due to increased salt intake. It's quite possible you were already retaining water, for whatever reason, and then you released it after a strength session. And, the muscles do not always retain water. It's mostly if you've stressed them with something they're not used to and you are feeling sore. At other times, strength training doesn't really affect the scale with any water weight.

This is one of those times you have to take the scale with a grain of salt and amuse yourself with it, but don't take it too seriously. Stick to plan. Just stick to the plan, give it time, and the weight will have a serious downward trend.

I knew that different perspectives would help. You guys always make me think differently. Is this sound thinking?

I don't sweat much if any in water aerobics (or yoga) although the fresh water pool does dehydrate me.

BP is 3 kg for 60 nonstop min and with plenty of reps, I sweat A LOT. I was sore in pecs, triceps and quads but nothing serious. (I learned that lesson! That's why its only 3 kg for now.)

Maybe raising my core temperature and requiring me to sweat has helped somehow. Although I am always hydrated, thinking back, I may have been getting up more often during the night.