You've got the hang of what to eat and drink to keep you skin moist, but to keep on properly moisturizing from the inside out, you also need to know what to avoid.
Alcohol acts as a diuretic, meaning it causes your body to create more urine, sending you on more frequent trips to the bathroom. Urinating more than usual can dehydrate you by causing you to lose fluid more quickly than normal [source: Mayo Clinic]. So, if you choose to consume alcohol, be sure to drink plenty of water with it to replace any lost fluids.
Caffeine has long been believed to act as a diuretic also, but this might not be so. It acts only as a mild diuretic, and you would have to consume more than 4 to 7 cups of a caffeinated drink per day in order to see the effects [sources: WebMD: Caffeine Myths, Zeratsky]. So, you don't necessarily have to give up that jolt of java, but you should at least be aware of how much caffeine you're drinking and what it can do to your skin. Caffeine lurks in coffee, tea, soda and energy drinks, so you may be consuming more of it than you think.
The bottom line with alcohol, and caffeine in extreme cases, is that if you are dehydrated, your skin isn't getting enough moisture and it can dry out. If you're trying to moisturize from the inside out, you will want to limit these drying culprits, or avoid them altogether.
Overall, drinking plenty of water, eating a variety of healthy foods and watching your caffeine and alcohol intake will put you on the road to healthy, moist and supple skin. For more information on moisturizing inside and out, follow the links on the next page.