Since you have asked specifically for information regarding fair hands and neck, I assume the rest of you is fair. Your hands and neck are exposed to the sun, and that is why the skin here is often darker than the skin on your face. Hyper pigmentation is another possible cause for the dark skin on your hands and neck. A variety of skin disorders also result in darkening of the skin. Therefore I would suggest that you visit a doctor in order to get a correct diagnosis.
One of the first things that you can do is to protect the skin on your hands and neck. Wear long sleeves when going out in the sun. Ensure that you carry an umbrella or wear high necked clothes when going out. Oatmeal, in combination with yoghurt, can work wonders on dark skin. Mix one tablespoon of oatmeal with one tablespoon of yoghurt. Apply this on your hands and neck. Let it dry. Then wash off. Even though there is no particular food item that is known to lighten skin color, eating food in balanced quantities can certainly help your skin look healthy. Oily food must be avoided. Alcohol and excessive amounts of caffeine are bad for the skin too. Instead, drink lots of water throughout the day. Eat fruits and vegetables and ensure that you lead a regulated life.
answered by G M