A basic tenet of anti-aging skin care is hydration. Keeping your body well-hydrated is the key to keeping skin looking young and healthy. Your body is more than 75 percent water and a lack of water can have an adverse effect on the function of skin cells. When cells operate at their optimal level, the body sheds dead skin at a faster rate, giving your skin a healthy look. However, a lack of water, combined with poor diet, has a diuretic effect on the body, which can cause your skin to look unhealthy and aged.