Stretch marks

Stretch marks are usually associated with pregnancy, but it can often be caused by rapid weight gain.
Also a diet low in fruit and vegetables and therefore vitamin C, can also cause stretch marks because vitamin C is essential to produce elastin and collagen, very important for the skin's condition.
Low levels of zinc are also a factor as zinc is very important for the healing of wounds.
Normally, stretch marks are more apparent in black and asian women, because of the skin's propensity to develop extra pigmentation in areas of scarring.
With stretch marks, prevention is definitely better than the cure as, once you have them, they will fade over time but not necessarily disappear.