40 year old female, 134lbs, 5'4, should I just let the fat set in & not try too hard before Vaser lipo?

Hello, I'm a 40 year old female, 134lbs 5'4 I've been thin all my life but for the past 2 years I've gained a few pounds and can't seem to get rid off. I'm considering a liposuction but my main question is this: Should I just let the fat set in and not try too hard before I do the lipo so the doctor can see how much fat needs to be taken off? My fear is if I try to lose 4-6lbs now before doing the lipo, the weight will come back. Is it a good idea to just leave it all alone and and do the lipo?