Whether you’re really heavy or ten or twenty pounds overweight, you know what a struggle it is to control your cravings. You may succeed for a few days, but then you just cant stop yourself. That is not matter of willpower. It’s a chemistry problem.

Cravings are a sudden obsession with a particular type of food—and they’re triggered mostly by messed-up body chemistry. When levels of the hormone estrogen fall, for example, levels of the brain neurotransmitter serotonin drop, and appetite increases. And when insulin is too high, you’d kill for a cookie, or maybe a whole box. This is why it’s so hard to just eat a little bit of something sweet. Your brain is signaling your body to crave more and more of a snack.

Eating refined carbs like cake, candy, cookies, or white bread raises serotonin and endorphins in the brain, creating a happy, peaceful state—which is why you turn to carbs when you’re anxious and stressed. These spikes of happy hormones make you calm only in the short term, however. You are literally self-medicating with food.

Some people crave sweets and others, bread. It doesn’t matter, because it all converts quickly to sugar in your body and feeds the cravings more. Fortunately, you can trick you system not to be hungry. Some tips to satisfy cravings the smart way:

• Reach for fruit when craving hits. Fruit is your best defense against insulin spikes and the resulting cravings.
• Be prepared. If you know that the afternoon is when you’re likely to crave junk, stash healthy snacks in your desk, like carrots, nuts, a low-cal protein bar, celery with peanut butter, hard-boiled eggs, or prepackaged foods under 150 calories and five grams of sugar.
• Move your body. People who exercise regularly have cravings. Why? Working out helps rebalance your hormones and increases feel-good chemicals in your body.