Learn how concentrated sugars, fats and salt manipulate our brain chemistry making us crave certain foods.

Why do we crave certain foods, and why is it hard to stop eating them once we start?

There’s a simple reason for this: in most cases, the foods we crave aren’t actually food. We tend to crave products that are “ultra-” processed and contain large quantities of concentrated sugar, salt and processed fats — manufactured calories. That’s very different from broccoli, milk, brown rice or hummus. Sugar doesn’t nourish; it entertains. And your body knows the difference. One important reason for cravings is that when you eat things that don’t nourish you, you stay hungry.

Have you ever wondered how you can eat a huge box of candy at the movies and still want dinner afterwards? Or why your brother measures his cookie intake in sleeves? — As in, “Yesterday, I ate a sleeve of thin-mint cookies after the game.” Sugar is the strongest stimulator of cravings. That’s why best-selling author Dr. Mark Hyman calls sugar a recreational drug.

There is a biochemical basis for physical cravings. Binging on specific foods, especially in large volumes, increases the brain’s appetite for those same foods that changed the brain in the first place. Furthermore, your own brain produces small amounts of opioids (yes, just like heroin and morphine) when you eat excess sugar and fat. No wonder you want more.

What causes cravings?

Food cravings stimulate certain brain neurotransmitters, like dopamine and serotonin. Dopamine enhances pleasure and well-being. Serotonin increases feelings of comfort, relaxation and security. Serotonin also reduces pain, including the psychological pain of anxiety and depression. When stress lowers serotonin levels, sugar steps in to stimulate serotonin release and reduce the pain.

“Hyper-palatable,” ultra-processed items change the neurochemistry of the pleasure center in the human brain. It’s not sugar or fat creating this problem per se, but rather large amounts of concentrated sugar and fat. Sugar, fat and salt also tend to be mutually reinforcing, so intake of any increases the likelihood of wanting the others.

Real food is very different from manufactured calories. As opposed to sweet potatoes and oatmeal, potato chips and sweet breakfast cereals change your brain chemistry so you are drawn to eat more and more.

Mechanisms of addiction

The sugar, salt and fats in processed foods stimulate your brain in a way parallel to the effects of drugs. Food addictions overlap with alcoholism and drug addiction. Like alcohol and narcotic addicts, the brains of binge eaters light up when they imagine their foods of choice. In fact, the D2 dopamine gene, a marker for alcoholism and drug addiction, has been found in some food-addicted adults who are not alcohol- or drug-addicted.

Like addictive drugs, which are concentrated forms of compounds the human brain makes naturally (but in tiny quantities), ultra-processed sugar and fat are also concentrated forms of foods found in much smaller quantities in your garden. Beets, dates and even sugar cane are not addictive foods. In nature, sugar is not found in a crystallized form — humans make it that way. But take away the fiber, the phytonutrients and the minerals, and all that remains is sugar crystals. Sugar is a stripped carbohydrate, a group that also includes white flour, corn starch and corn syrup. Remove the bran, husk and germ, and all that remains is a pellet of starch or sugar. Both starch and sugar overstimulate brain receptors and compromise nutrition. Reduce your cravings by cutting sugar and white flour.

Even if you know that it causes chronic diseases (like obesity, diabetes, fatty liver, strokes and heart attacks), sugar still gets your brain hooked. It’s very hard to avoid. Enormous quantities of sugar are hidden in processed items, even ones you don’t think of as sweet. Overeaters Anonymous maintains a list of 99 ways sugar can be listed as an ingredient.

Another cause of cravings relates to absorption rates. In nature, even the sweetest foods, like pineapple and dates, hold their sugar inside a fiber matrix that takes time to break apart and digest. But concentrated sugar, stripped from its source (mostly fruit), requires gobs of insulin to catch and escort it to your cells. That often causes low blood sugar, which makes you hungry again, usually for a quick fix of more concentrated sugar that triggers a second insulin surge and a repeat episode of low blood sugar.

Sugar is not the only problem. Manufactured fats are also involved in stimulating your brain to want more. And your biological desire for salt gets ratcheted up several notches when fat enters the picture. Fat plus salt creates crunch (e.g., crackers, chips), and crunch is irresistible.

Better solutions for stress

Finally, no article about cravings and overeating would be complete without a few words about stress. Stress can be an important factor in overeating. The greater the disconnect between your natural need for comfort and the degree to which it is unmet, the greater the likelihood that you will find it in food. If this resonates, you might want to consider getting a pet. Not only might it meet your cuddle-quotient but taking a dog for daily walks will increase your activity level. With or without a pet, exercise is a powerful mood stabilizer. That’s a win-win.

Dr. Roxanne B Sukol is a graduate of Case Western Reserve University School of Medicine and is board certified in Internal Medicine. She is Medical Director of Cleveland Clinic Wellness Enterprise and authors the blog Your Health is on Your Plate. Her essays have been published in the Cleveland Plain Dealer, Wall Street Journal Online, JAMA and more. She is a recipient of awards from the Baltimore Review Creative Nonfiction Competition, and the John Conley Foundation for Ethics and Philosophy in Medicine.