Nanda, I have no idea of who your trainers are, but do NOT buy into that for a minute. I know mothers sometimes have a problem with fat, but, unfortunately, unless you are a Hollywood movie Star, and have the time and money to get one on one training, diet and nutrition help, you're going to have to do it the old fashioned way. Some powerlifters wear a belt, , but it's for back/midsection stabilization for when lifting in competition for maximum , all out, lifts. And even then, they don't snug them up too tight (OK< maybe some go overboard), but bear in mind, if you snug them too tight, and you squat or deadlift too much, it causes the pressure to go downwards below the belt, and into your lower intestines, possibly causing a hernia. Trust me, I know, that's how I got my hernia, twice. As far as any heat, causing fat to melt, throw that into the category of "snake oil medicine". Watch your diet, read some of the stuff Ironmaiden Stickied in the Diet and Nutrition section, and a lot of Berardi's articles, coupled with exercise of your choice, and you should be fine. May not go away overnight, but give it a shot, and it will go.
Best to you