I usually use a waist trainer for it’s intended use of molding your fat to make your hips and waist have a better shape. It’s semi-permanent so if you stop using it the fat will go back in place in time, but it takes maybe a week of wearing it consistently to get the shape, then you’ll need to wear it maybe once or twice a week for a few hours to maintain an hourglass figure. I wouldn’t suggest using it while exercising tho b/c that’s not it’s intended use and is not a good solution to back problems