The more you sweat, the more you lose. You burn anywhere between 300-500 calories in 20 to 30 minute via sauna waist trainer and this equals 5 pounds. Slimming sweat vest helps to tighten belly and firm your abdomen Sauna vest with zipper intensifies perspiration in your core by up to 3 times more than regular gym clothing,sauna suit fits snuggly around your midsection, working its magic from your shoulders, down to your waistline, work as waist trimmer, meanwhile helps posture for back and abs as you workout 10mm Neoprene not only produce heat to make you hot and sweat like crazy when workout, but keeps your body warm during cold days with minimal thermal cover, if you work in a cold place you are able to stay warm when wearing this sauna tank top Men corset training vest can be worn under or over any regular shirts, invisible sauna trainer vest, can't see it under your shirts when you workout please select the black one Reversible waist trainer vest for men doesnt stink too much after prolonged use, easy clean and hand washable, please hang it outside to air dry