It's officially 2013, and it's time to start drinking at least eight glasses of water a day. We've all heard that drinking water is good for our skin, but here's why you really need to be drinking all of that H2O. Medical aesthetician Craig Shishido of San Francisco's Gentle Star Medspa explains how drinking water is good for your skin. "I always kind of equate skin to be kind of like your kitchen sponge," Shishido explains. "If you look at your kitchen sponge, when it is dry, it is pretty contracted, shriveled, and rigid, so it's hard to bend. But if you put it under your sink and turn on the water, then all of a sudden the sponge expands." And just like a sponge, your skin needs that moisture to expand. "If you dehydrate your skin with caffeine, alcohol, or just lack of water, your skin does contract like the sponge in your sink, too," says Shishido. "So when you drink water, basically you reach a higher level of potential of expanding the moisture potential of your skin." And expanding the moisture potential of your skin is linked directly to your pores. When the skin is dehydrated, the pores are more firm and rigid, just like the "pores" of a dehydrated sponge. But hydrated skin has more flexible pores, which are then able to stretch and release naturally secreted oils. "The dehydrated pores do not flex," Shishido explains. "And then you have a better chance of getting bumps, future acne, or even blackheads. So the more pliable your pores are, the more able it is to release what needs to come out. And then once it's released, it will contract back to what you ultimately want: tighter pores."