I have a paunch, probably not as big as most, but that's how I fee when I see it in the mirror. This is why I bought this belt.
Having used it for months, I was able to figure out that it sort of works. The first thing is to point out, DO NOT USE THIS if you are seriously working out using moves such as squats or deadlifts. You will need more support than this provides. This belt will be for the average user, not a serious gym-goer. Let me explain...
I used it when cycling to work, during my cardio workouts, basic free weights and yoga. For this, it's great!
During all my activities I did find this worked well, it kept my core temperature higher than normal. The fitted nature of the belt, helped me concentrate more on my core. When I took it off, sorry, there was a lot of sweat. Which is exactly what you want to see. During my cardio exercises, I did notice that it provided a little extra lower back support than without it. Which is great for when you are doing jump training. Yoga with the belt is also excellent, as it helps you focus on tightening the core muscles during the different poses.
After several months of using this, the paunch is still there, but it has gone down. The belt does help, but not as much as I had initially thought it would.