Extreme weight loss, dieting and increased exercising can cause fat loss from the face and body. This extends to illnesses that cause weight loss such as cancer, bulimia, anorexia nervosa, and TB.
The skin also becomes thinner and loses elasticity. This is due to loss of collagen and elastin, the proteins responsible for keeping the skin plump, firm, and elastic. Hence, the skin is lax and begins to sag and contributes to the appearance of sunken cheeks.
Smoking aids this process by reducing blood flow to skin, and nicotine destroys and contributes to decreased synthesis of new collagen and elastin. The environment can also affect the supply of nutrients from blood vessels to the skin. If the skin is regularly exposed to harsh weather conditions, it will result in reduced thickness and elasticity.
You can achieve a real difference in your face without downtime and the expense of invasive surgical procedures.