Yes, I had this done years ago. I wish I still fit into them! The tailor took in the seam from the middle of the tush up to the waistband, and then took in the waistband. I don't think the sides were affected at all. It wasn't cheap because the tailor had to alter multiple seams and open the waistband (which is a pain - I sew and always try to avoid this). However, the pants looked great for the following few years.

It's hard to take in pants in the seat -- but is it the butt or the hips?

If you can pin or pinch out the fabric to get the fit you want, then a tailor can fix them.

I should add that even if there is not a split waistband the waist can be taken in by adding darts above the butt.

If it is a split waistband it is much easier to tailor. Lapped seems are much harder. See if there are outlets of extra material in the seat of the pants - meaning - do the pants have extra material beyond the seem on the inside of the center seam on the inside of the pants. If so it can be easily opened and the seat can be taken in. If it's like jeans where the two pieces of material are folded over one another and sewn then they cannot be taken out or brought in at the seat.

Jeans are not easy to alter except for simple hems. The fabric is very thick. Also you probably won't be able to undo it because of the uneven fading. I would just buy new jeans. Dress pants might be different.

Also, could they alter them in suchc a way that if I went back up to that size I could have them taken out again?

It's actually closer to 10 lbs, and not planning to put it back on (but you never know).

I have a predicament, granted its a nice one to be in! I have lost some weight recently, about 7 lbs. It seems that because if that I've gone down a size, or maybe have just ended up between sizes.

My problem is I have several nice pairs of jeans and pants that are big on me now in the butt and waist. The butt area of the pants looks saggy when I like them a little tighter. I can sometimes get the waist tighter with a belt but sometimes that makes the belt look too tight and cinched.

I was thinking of having all the pants, or at least a few of my favorites, tailored. Can a tailor take in pants at the waist, and especially the butt, to take them down a whole or half size? I mean I've had clothes tailored before but they were minor alterations, taking in a pinch here or there.

Id buy some new smaller clothes but a bunch of these pairs are new within the last few months, and not cheap!