As we get older, hormonal changes can lead to decreases in collagen, Hirsch says. And weight loss can make this more noticeable. "Think of the face as a sofa," she says. "In the past, when the sofa started to age and sag, women had work done to pull the slipcover—or the skin—tighter. Now we know that one of the most convincing ways to make it look younger is to re-inflate the pillows." The latest technique dermatologists use to restore fullness involves injecting the face with various soft-tissue fillers, says Hirsch, but adds that you can "protect your facial pillows naturally" by maintaining a healthy, not-too-thin weight.