Thick lines are a kind of dry lines. Shrinking is a phenomenon that skin fibers break during pregnancy, fitness and sudden weight gain, showing red, white or purple stripes. It also includes obesity lines and motion cracks. In addition to the abdomen, there are body parts such as the inner and outer thighs, knees, buttocks, lumbosacral and so on.

The abdominal wall tissues of human body are skin, skin elastic fibers, subcutaneous fat layer, rectus abdominis composed of muscle fibers and tendons, preperitoneal fat layer and peritoneum from outside to inside. Under normal circumstances, the skin elastic fibers and rectus abdominis maintain certain elasticity, and they can expand and contract freely within a certain limit. The broken skin fibers form an obesity line during the sudden weight gain.

After losing weight, the broken elastic fiber is gradually repaired, but it is difficult to return to the previous state. The original cracks on the skin gradually faded and finally became silvery dry lines.