This ingredient is a humectant that pulls water into the outer layer of the skin and holds up to 1,000 times its weight in water, says Zeichner. He likes Neutrogena Hydroboost ($20, ulta.com), an editor-tested, refreshing, gel-like formula that feels light yet acts like a heavy moisturizer. To maximize hydration, apply it when your skin is damp. The same theory applies to the skin on your body: “Moisturize within five minutes of getting out of the shower to lock in hydration,” Zeichner says. “Studies have shown immediate hydration to be more effective than delayed hydration. So apply body lotion swiftly and keep the bathroom door closed to increase humidity in the air. When choosing a body moisturizer, look for ceramides on the ingredient list. These help seal in the cracks between the outer skin cells.” His pick: CeraVe Moisturizing Cream ($11, amazon.com).