Q: My skin becomes really dry in the winter. It becomes sensitive and flakes for no reason. Each time I apply makeup it peels off my dry skin! Please help! (Susanna W, via email)

A.  Our skin really needs extra attention in winter when the lack of humidity in cold air causes the upper layers of the skin to lose large amounts of moisture and leaves skin feeling dry. According to Dr. Jerome Litt, MD, assistant clinical professor of dermatology at Cleveland's Case Western Reserve University, when ambient relative humidity dips below 40 percent, moisture from the skin passes into the surrounding air and skin becomes dry.

"Dry skin is not caused by a lack of oil, as was once thought, but by water loss from the skin's outer layers," adds Dr. Litt.

Prevent dry skin from within: drink at least 64 ounces (or eight glasses) of water a day to help keep your body and skin well hydrated.

Although skin produces an oil—called sebum—that slows water evaporation from the surface of the skin, sebum cannot prevent dryness if skin lacks moisture. Other factors that can dry skin by depleting it of water and its protective oils include wind and sun exposure, harsh alkaline soaps, some oral medications, dietary deficiencies, and indoor heating systems, which sap moisture from the air.

Invest in a humidifier, exfoliate with oatmeal and green tea regularly, and avoid harsh cleansers that contain alcohol. Instead cleanse your face with cleansing oils and add a few drops of a facial oil serum underneath your moisturizer.