Stretch marks appear on the skin due to the tearing of the dermis (a skin layer). Stretch marks are usually the result of body volume growth. When the volume of a body rapidly increases, some tissues in the deep layers of the skin can not sustain the pressure and they tear.
These changes can happen at different times in life an for various reasons but the most common causes are: sudden increase of body volume (such as pregnancy), hormonal changes such as puberty, the general health of the skin (which is closely related to what you eat), etc. There are also some ethnic groups that are more inclined to have stretch marks. Although stretch marks don't usually cause pain, at the beginning they leave red marks on the skin and as time goes by they become lighter until they look white. To prevent stretch marks there are several tips to take into account such as avoiding abrupt changes in body volume gain or body volume loss, another important fact is skin hydration which can be controlled with the use of moisturizing creams or oils and with constant consumption of water (to hydrate the inner body), you should also follow a balanced diet, etc. On the other hand, there are tricks that can help conceal them and even make them disappear such as applying a blend of beetroot shells, carrot and peach juice on the stretch marks, or the use of other remedies and products that can help you remove them.