Waist training has become one of the most dangerous fitness trends of 2016. The body-shaping corsets are said to reduce your waist size and accentuate your curves. Although they do what they promise, wearing one may not be worth the risk. Waist trainers put too much pressure on your lungs and ribs, which makes it hard to breathe. According to USA Today, long-term use may cause permanent organ and nerve damage.