It could be a diet thing, it could be other things. If you've changed shampoo or conditioner, it might be causing it, either because residue remains or its clogging your pores when you rinse it.
Also, because it's winter, if you're using a facial cleanser together with the dryness of heating, and general winter air, it can dry your skin out. Your skin will respond by producing more oil which will in turn clog your pores and cause you to break out.
You might need to change your sheets
Your hair might be in your face too much
Could be hormones (guys do actually have a biological cycle that's just not as obvious as girls)
Lack of exercise can upset your skin and in some people it can irritate already existing acne.
An allergy can irritate it further.
Any of those sound reasonable?
If it IS dryness, you're best to go to a dermatologist to get a good, mild, hypo-allergenic moisturizer, but if you don't have free health care where you live, you can also try very basic moisturizers from the drug store. Just be careful because some can clog your pores, or they can contain toxins. You can check toxicity by looking up moisturizers (or any cosmetic product) here:
http://www.cosmeticsdatabase.com/splash.php?URI=%2Findex.phpALternatively, when my skin gets dry what I do is crush strawberries with some milk and put it on my face (make sure it's clean and so are your hands). It feels good and it helps ease the dryness.