I’ve heard people debate it before. I’ve felt it, before. And I’ve heard Robb Wolf discuss it before. And the general consensus is that food is an addictive substance. Eating can be a positively reinforced habit that our brains constantly crave. The worse part, however, is that we can never go “cold turkey” off of food. With each meal we are forced to recondition the habit. “Relapse” constantly threatens us. This makes food, science is beginning to show, more difficult to kick than hard drugs. Yikes.
Research shows that all drugs—alcohol, nicotine, cocaine, heroin, and foods, particularly sweet foods—are habit forming in like ways. They overstimulate the brain’s reward system, which creates a vicious cycle of dopamine supply and demand.
This “reward system” consists of a circuit of neurons that run through the ventral tegmental area, the nucleus accumbens and the prefrontal cortex in the brain. It is normally activated when an animal does things–such as eating or sex–that help it to survive. This activity increases levels of pleasure-related hormones such as dopamine and serotonin. This is natural, and this is awesome. What is not awesome is when drugs overactivate the circuit, and dopamine levels soar. Dopamine receptors get blown out, such that we are now forced to conduct our lives with a malfunctioning dopamine system (this is the same thing ecstasy does to our serotonin receptors). We learn to mitigate this “deficiency” with whatever drug caused it in the first place. One whole banana cream pie, please.
This also means that addictions worsen over time. What may start out as an innocent habit, such as always going to the fridge when you get home from work, some day may not feel like enough. So instead of having a salad at that time, now you crave fruit. Or cheese. Or fruit cheesecake (mmm). And in a year you’re coming home and used to downing a big gulp and a whole bag of chips. These things happen to us, and they happen so slowly that we never notice until we try to stop and realize that we can’t.
Because, as I mentioned above, food is a constant in our lives. It isn’t going away. We need to de-condition the pleasure response, and we need to kick certain foods to the curb for good, but it’s very tricky business, staying alive and healthy and doing so at the same time. After someone dependent on a substance stops using it, it often takes time for depleted dopamine receptors to return to baseline levels. I find that my need to eat decreases with how often I eat, and I suspect that this is because my brain has adjusted to more normal dopamine levels during that time period. I also find that my need to eat decreases drastically when I don’t eat carbohydrates, something I’ve discussed before, and is definitely worth keeping in mind.
To quit an addictive cycle, low dopamine levels must be tolerated, but only for a given period of time. For mice addicted to cocaine, it can take two days to regain normalized levels. For rats in one study on food addiction, it took two weeks.
To gauge just how much the quantity of dopamine receptors had affected these rats’ eating behavior, Kenny and Johnson of the Scripps Research Institute of Florida inserted a virus into the brains of a test group of the animals to knock out some dopamine receptors. The researchers found that– rather than gradually increasing reward thresholds and accompanying overeating behavior— the dopamine deficient rats took to overeating immediately when given access to a high-fat, high carbohydrate diet.
So the researchers designed an experiment to try to draw a human parallel with the rats, training them to expect an electric shock when they saw a certain light cue. Unlike their plain old chow-fed counterparts (a mix of sprouts and vegetable oils and other crap), obese rats accustomed to food rewards would keep right on gorging even when they knew a shock was coming.
But these are rats!, you protest. Does the same apply to humans?
You bet your sweet ass it does.
Gene-Jack Wang and Nora Volkow of the Brookhaven National Laboratory discovered that obese people share that dopamine deficiency with many cocaine and alcohol abusers. Their study injected 20 volunteers–10 obese subjects and 10 control subjects– with a radioactive chemical tag designed to bind to dopamine receptors in the brain. Then they scanned these individuals using positron emission tomography and counted the numbers of receptors they saw. The obese subjects not only had fewer dopamine receptors than did the normal-weight subjects, but the number of receptors was lower for patients who were heavier. With increasing weight, and presumably increasingly “unhealthy” diets, dopamine levels decreased. People who are conditioned to get dopamine from foods need more and more as their addictions worsen.
There is a lot of discussion in the scientific community about genetics, and how it plays a role in chemical addiction. While true that some people are more susceptible than others, I don’t really fucking care. Two rats in the whole study above abstained from bingeing. Two. Fuck those two. We’re all susceptible. The lesson here isn’t that science is going to find some miracle to cure addiction (though of course we’ve all got our fingers crossed) or even that it’s going to be able to tell us who is most susceptible to the addiction demon, but rather that we’ve all got to be careful.
And we have just got to forgive ourselves if we find that we have food addictions or habits. Food can never (and should never) be eliminated from our lives, so we are forced to confront disordered behaviors while continually interacting with our demons. It’s hard as shit, and if you hate yourself for struggling I will come right to your house and shake you. Depression and feelings of self-loathing decrease dopamine levels, so every time you have negative feelings about yourself you are only helping the monster.
Addiction is nasty, but it’s not unconquerable. Long roads and enduring positivity are the names of the game. Breathe. Love. Breathe. Love.