I have lost about 100 pounds over the past few years, focusing primarily on weight loss. Now that I have lost the weight, and I look kind of scrawny underneath what was fat, I'm trying to gain muscle mass.

I can't see a change in my appearance, at least not yet, because I have only gained 10 pounds since I started attempting to gain muscle, and if anything, I am more toned in my arms, ***but my pants are getting tighter again!***

I have been doing the following exercises among others:

1. Planks
2. Side-planks
3. Back extensions

They all target the area around where I wear my pants; **is this normal for muscle gain to make a noticeable difference in 2-3 weeks on waist/hip size for pants?**

The difference isn't even one belt notch yet, but I am hyper-aware of how my pants fit.