With no exercise I lose weight, and go down to about 124. When I exercise I gain weight and stay around 130-5. No difference in diet except I eat more on the days I work out. I go running for thirty minutes three days a week. Don't really understand what's up.
Ya i believe its called muscles, your body lose the fat and replace it with heavier muscles.
I don't really notice any extra muscly bits.
I used to freak out every time I weighted myself the day after I had done weight lifting. It took me about half a year before I realised that it was water retention, and stopped weighting myself the days after I had done heavy weight lifting. With that being said, throw away the scale! It won't do you any good.
I have a scale that can show body fat percentage and skeletal mass (muscle) percentage. For the past month or two I have been extra active with biking and jogging. My weight has been going up but my scale shows fat is declining and muscle is increasing. You do mention eating more and that can be a factor as well. If you exercise and have an increased appetite, eat more. Nothing else should be recommended. However, years ago (well prior to my current lifestyle) when I was new to cycling, I would bike for 60 or 80 miles then come home, order and eat a large pizza, then sleep for the rest of the day. My body weight started to grow out of control with those habits.
Do you physically look different? Do you notice the weight gain?