By Neal D. Barnard, MD Adjunct Associate Professor of Medicine at the George Washington University School of Medicine President of the Physicians Committee for Responsible Medicine in Washington, DC Author of the 21-Day Weight Loss Kickstart
Can foods be addictive? So many of us ask exactly that question when a sugary doughnut or a gooey cheese pizza call to us so insistently. Scientists have debated the question, too. Some hold that certain foods really do behave like addictive drugs, while others give foods a not-guilty verdict, saying that overeating is simply an emotional problem. But once we gained the ability to understand what is actually happening inside the brain, we gained a whole new perspective.
Here’s what we’ve learned: When sugar hits your tongue, it triggers the release of feel-good chemicals in the brain in the same way that intense exercise triggers the “runner’s high.” Like weak versions of heroin or morphine, these natural opiates can get you hooked on whatever food triggered them. That’s exactly what sugar does. As sugar touches your taste buds, it sends nerve impulses to the brain, triggers the release of opiates, and makes you want to come back for more. And more powerful than pure sugar is the combination of sugar and fat. Think of the mixture of sugar and butter or shortening in a cookie, cake or pie. They tend to call to us much more than sugar itself.
Chocolate is similar, as University of Michigan researchers proved, using the medication naloxone. Normally, this drug is used to treat heroin overdose, because it stops heroin from attaching to receptors on brain cells. The research team gave naloxone, not to heroin addicts, but to chocolate lovers – people who really tended to binge on chocolate. After infusing the drug intravenously, the researchers offered a tray of chocolate candies. It turned out that chocolate had lost much of its appeal, showing that the lure of chocolate is not all taste and mouth-feel. Rather, chocolate hijacks your brain chemistry, triggering the same receptors that heroin affects, and when researchers block that brain effect with naloxone, much of chocolate’s attraction is gone.
We can now clearly say that both sugar and chocolate have powerful effects on brain chemistry. But apples, bananas, oranges and a cool summer salad – tasty though they may be – do not. Let’s face it, no one ever went to a convenience store at nine at night to buy an apple. We go there for junk food.
Could meat be similar? When you hear a man say, “I’d rather die than give up my grill,” it starts to sound like he’s hooked. And, indeed, British researchers found that opiate-blocking drugs reduce the desire for meat, just as they do for chocolate, showing that the desire for meat comes at least in part, from its effect on the brain.
Cheese is a special case. Yes, it’s about 70 percent fat, loaded with cholesterol and sodium, and smells like old socks. But many people are absolutely hooked on it, calories and all.
Here’s why: the main protein in milk and cheese is called casein. As you digest casein, it breaks apart to release opiates, called casomorphins – that is, casein-derived morphine-like chemicals. Shortly after you swallow a bite of cheese pizza, these chemicals enter your bloodstream and pass to your brain and attach to your opiate receptors.
Casomorphins’ natural function, presumably, is to provide a bit of feel-good sensation to a nursing calf. And because a calf is weaned very soon, the fat, cholesterol and sodium in milk products are not a problem. But humans who get hooked on these same compounds can easily run into trouble as the years go by.
So, which foods affect the brain and are potentially addicting? Science suggests that there are four: sugar, chocolate, meat and cheese. The next question is, does it matter? I would argue that, if you’re having just the occasional taste of sugar or chocolate, it does not matter. But if your waistline is expanding before your very eyes or you’ve developed health problems, it’s time to take it seriously.
If you’re in that situation, you will very likely find it easier to avoid teasing yourself with even small amounts of an addicting food. Just as smokers find it is easier to quit, rather than to try to moderate tobacco use, the same seems to be true of food.
When you’re trying to break any habit, it pays to get plenty of rest, exercise regularly so you feel your best, and ask your friends or family to not tempt you with whatever you’re trying to break away from. Many, many people have set aside unhealthful foods, and they end up feeling so much better as a result.