I never tried those belts but I'm sure they work to contract your muscles. Now... do they work to help you lose weight? I guess YMMV. All these gadgets targeted to work your abs are misleading because there is no such thing as spot reduction of body fat. If you're exercising to burn calories, you lose fat all over... not just in your gut or thighs. Using an ab-belt is still doing exercise... it's just not as voluntary. Cardio-vascular exercise works best to burn fat and ab-belts don't do that.