You know how it goes: You start thinking about a particular food, and pretty soon you can’t get it off your mind. You substitute a healthy snack instead, but that just doesn’t hit the spot. Pretty soon your craving has become a full-blown obsession. You spend a few days fighting it, but before long you find yourself in the late-night drive-through line, hanging your head in shame as you order a super-sized combo and a large milkshake.

Why does this happen?

Science provides six explanations, one (or several) of which might apply to you. Knowing where your craving originates is half of the battle; once you’ve identified the source, you can take appropriate steps to beat your obsession.

Dehydration. Many of us are walking with chronic dehydration, which often manifests as uncontrollable hunger instead of thirst. Carry a water bottle, and drink 4 to 8 ounces when cravings strike. Wait 10 t0 20 minutes, and you might often find that the craving disappears.

Hormones. Women in particular battle hormonal food cravings. The fluctuations in your monthly cycle can trigger cravings for salty or sweet snacks. Fight back against PMS by exercising regularly, practicing meditation, and reminding yourself that these feelings – and the accompanying cravings – will pass in a few days.

Low blood sugar. Oddly enough, eating a diet high in sugar can actually cause blood sugar crashes, which will usually cause you to crave even more sugar! Intense workouts can also trigger a blood sugar drop. Fuel up with protein regularly to keep your blood sugar levels more even.

Boredom. If you’ve put yourself on an overly restrictive diet, you’re setting yourself up to subconsciously believe that the “forbidden fruit” tastes sweeter. Don’t decide that any foods are completely off-limits, unless of course you have a medical reason for doing so. Allow small amounts of “bad” foods, and they will have less power over you.

Emotional eating. If your cravings are triggered by stress, loneliness, sadness, and other negative moods, try addressing them with non-food solutions first. Exercise, meditation, calling a friend, journaling, aromatherapy, or practicing a favorite hobby are all healthier methods of of dealing with negative emotions.

Lack of sleep. If you aren’t getting enough sleep, chances are good that your appetite hormones are out of whack. For most people, this problem is easily corrected: Identify what is keeping you up at night, and take the appropriate steps to correct it.