Ive found this waist trainer to be VERY useful! Im currently a size 14, with a large middle-38 sucked in. The 4X at the tightest fits perfectly. Since I am currently losing weight, Im ordering the next size down (3X). Not only does this waist trainer pull my stomach in at least 2 1/2 inches, but helps me with my posture..forcing me to not slouch, which my trainer says will happen with a large middle.