Caffeine causes unstable blood sugar which then causes cravings. Unstable blood sugar = cravings. Anything with caffeine will cause you to crave, even diet sodas. If you drink coffee regularly you're probably addicted to caffeine so it may not feel so great for the first few days as you go through withdrawals. This is a real stumbling block for many dieters but if you can get the caffeine out of your system, you'll feel much better.