Junk food desensitizes the reward centers of the brain



Dr. Fuhrman’s concept of toxic hunger states that the unhealthy foods at the center of the standard American diet are addictive. Like all other drugs, addictive substances involve both pleasure and pain. By definition, an addictive substance is toxic and therefore produces uncomfortable withdrawal symptoms when the body attempts to detoxify the waste products left behind. When we feel this discomfort, eating relieves the symptoms – when the body begins digestion it stops detoxification. So we mistakenly believe that these feelings are hunger, and we are then almost forced to eat too frequently in order to lessen the withdrawal symptoms from our low nutrient diets. This leads us to progressively eat more and more of the addictive food, and makes becoming overweight inevitable. Dr. Fuhrman further asserts that foods, lacking sufficient micronutrients, lead to a buildup of oxidative stress, free radicals and other inflammatory substances that are mobilized during catabolism causing distressful symptoms curtailed by overeating. 

Scientists studying addiction are now confirming Dr. Fuhrman’s assertion that unhealthy food is indeed addictive. Scientists following up their preliminary data on the subject

have published a new study in Nature Neuroscience showing that drug addiction and compulsive eating have the same effects on the brain – they desensitize brain reward circuits.1 In the brain, eating is motivated by pleasure and reward. 

The researchers studied three groups of rats – all three groups were allowed access to their standard (healthy) chow at all times. In addition, rats had either no access, restricted access (1 hour per day), or extended access (18-23 hours per day) to palatable energy dense food for 40 days. This palatable energy dense food consisted of nutrient deficient processed foods readily available to humans – things like sausage, bacon, and cheesecake.2

Extended access rats gained weight rapidly, and were significantly heavier than chow only or restricted access rats. Their calorie intake was almost double that of the chow only rats. Even the restricted access rats developed binge-like eating behaviors, getting about 66% of their daily calories during their 1 hour of access to the unhealthy food. 

The scientists used electrodes to measure the rats’ reward thresholds. The reward threshold is the minimum amount of stimulation that produces feelings of satisfaction. As the experiment continued, extended access rats had progressively higher reward thresholds. This means that their reward circuitry became less and less responsive, and a greater amount of unhealthy food was therefore required to satisfy their appetites. Even when the rats were taught to anticipate an electric shock, they kept eating, not even trying to avoid the shocks. This compulsive behavior in the face of negative consequences is a hallmark of addiction.

The scientists traced these effects to a decrease in levels of specific dopamine receptors in the striatum region of the brain. These exact neurobiological changes have been shown to occur in rats that are given extended access to heroin or cocaine. In fact, after access to the unhealthy food was no longer permitted, withdrawal (measured by continued elevation of the reward threshold) persisted in these rats for a full 14 days - rats in withdrawal from cocaine have been reported to experience withdrawal for only 48 hours. These results demonstrate how powerfully addictive – and powerfully toxic – unhealthy food is.

In the Western world, we have extended access to unhealthy food – nutrient-deficient processed food seems to be everywhere we turn. In such an environment, it is almost inevitable that we will become addicted, progressively gain weight, and suffer the health consequences. Only by removing the toxic, addictive foods from our diets and replacing them with health promoting foods can we break the cycle of toxic hunger and achieve excellent health.



1. Johnson PM, Kenny PJ. Dopamine D2 receptors in addiction-like reward dysfunction and compulsive eating in obese rats. Nat Neurosci. 2010 Mar 28. [Epub ahead of print]

2. Scripps Research Institute (2010, March 29). Compulsive eating shares addictive biochemical mechanism with cocaine, heroin abuse, study shows. ScienceDaily. Retrieved April 16, 2010, from http://www.sciencedaily.com/releases/2010/03/100328170243.htm

Food Navigator. Food addiction: Fat may rewire brain like hard drugs. http://www.foodnavigator.com/Science-Nutrition/Food-addiction-Fat-may-rewire-brain-like-hard-drugs/?c=DFrDdGqlXj9PxLeDW0x8cw%3D%3D&utm_source=newsletter_daily&utm_medium=email&utm_campaign=Newsletter%2BDaily

NewScientist: Junk-fed rats have ‘drug-addict’ brains. http://www.newscientist.com/article/dn18706-junkfed-rats-have-drug-addict-brains.html?DCMP=OTC-rss&nsref=health


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Comments (7) Read through and enter the discussion with the form at the end
david ashworth - April 26, 2010 11:01 AM

Dopamine receptors? Ah, well, as research goes, so far, so good. We've been on what we call a "Furhman-friendly" diet for seven months now. On the one hand, we feel great (!), we've lost weight -- over 12 for her and two sizes and 8 for me only 1 size -- and we can't stand the smell of cooking meat. On the other hand, Mr. Sugar and I have done the dance called 14 days of withdrawal umpteen times. He wins, 'long 'bout Day 2 or 3 or 4. (Blue Agave, anyone?) I'll be delighted when research shows how my micronutrient diet can also include a craving suppressor to break the cycle of toxic hunger.

Cindy - April 26, 2010 11:04 AM

These valuable studies are a first step to helping people understand why they are so driven to eat junk food. But it's important that they don't feel powerless when surrounded and overwhelmed by the SAD. Thank you, Dr. Fuhrman, for spreading the message of hope thru nutritarianism.

Allen McCollum - April 26, 2010 11:04 AM

Dr. Fuhrman,

Thank you for continuing to publish this information. Your effort in researching and documenting this material for us is appreciated!

mmk - April 26, 2010 11:44 AM

I definitely agree with this. I also think that many foods, particulary from chain restaurants (MacDonalds, Applebees, etc.) have ingredients that make it taste good and make us want more. Speaking of restaurants I went to Cheesecake Factory for a friends birthday and there was hardly anything I wanted to eat on the menu; now that the calorie counts are on there it blows me away. My friends ordered 2000 calorie plates, followed by cheesecake, no problem. I couldn't believe it!! I was disgusted and not to mention sick to my stomach, literally, the next morning.

Ginger - April 26, 2010 4:29 PM

Great article.

I too have experienced the lack of food cravings after staying away from stimulating foods for a time. Dr. Fuhrman, Dr. Christopher, and James Simmons have given me new hope and a new direction. Eating out used to be our favorite date and what we did with out of town family. We have a lot to rethink.

js - April 26, 2010 5:19 PM

mmk, cheesecake factory actually has a couple of really good salads with lots of veggies. you just have to tell them to hold a couple of ingredients (usually cheese) and put the dressing on the side. AND I think you can order a bowl of fresh strawberries for dessert. It's still gross to watch what other people order, though. . .

diane lassen - April 27, 2010 5:12 AM

There is no question that processed fast foods and sugary snacks are made to be addictive. Loads of chemistry and research are put into the production of these products to encourage us to eat them. Will power is no match for these foods, which is wht me MUST stay away from processed foods at all costs. That said, the natural desire to eat sweet food (along with the other tastes) is a part of our genetic makeup and some do better handling it than others. As a health counselor, some of my clients, myself included, always have a latent desire for sugar (me in the form of dark chocolate) no matter how long we eata clean, veggiful diet. Others can abstain and the callings go away. I even have some clients that, as long as they know they can have a tiny bit of something sweet, do well avoiding sugar altogether. It is truly understanding what our bodies are teling us that is key to moving away from unhealthful food choices and choosing health-promoting foods instead. DEprivation does not work for everyone, so learning what works for you is paramount! I know for my self, a vegan for 18 months and now one who eats some fish and eggs, I keep a dark chocolate bar in my desk at all times. I may ignore it for weeks, but then again, I knowit's there if I so choose to nibble! It is important that when we do decide to eat something "forbidden" that we do so openly, mindfully and joyfully, not embarrassed, in hiding or guiltfully.

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