Under normal conditions it is clear that drugs and food are very different, however, because the brain reward systems responsible for making drugs of abuse so addictive are the same pleasure systems that are activated by the foods we eat, our brains can have a very hard time differentiating between the pleasure derived from mild doses of some drugs of abuse and some types of food. What are the primary differences between food and drugs of abuse, and how might these differences actually help contribute to food addiction?
One of the key differences between food and drugs of abuse is that we need food to survive, but we don’t need drugs of abuse. Interestingly, however, the survival value of food is one of the factors that may contribute to its addictive potential. Food is one of our basic needs, and thus our brains are designed to make us enjoy the taste of it and seek it when we are hungry. This explains why some people go to extreme lengths when they are faced with severe hunger (e.g., stealing, cannibalism), which emphasizes what a powerful motivator food can be.
As a species, we need to eat and mate to survive so our clever brains make us enjoy those activities. That enjoyment occurs through the activation of the same reward systems that are activated by drugs of abuse. Drugs of abuse actually “hijack” the primitive brain systems that were put in place to reinforce natural behaviors, such as feeding. Because of this, the brain circuitry is certainly in place for food to also elicit addictive responses.
Another basic factor that separates food from drugs of abuse is its availability. For most people in industrialized nations, food is ubiquitous. It can be found walking down a city block, driving down a local highway, or by ordering delivery. Drugs of abuse, on the other hand, are typically less accessible. A third feature that distinguishes the two is the constant exposure we have to delicious and inviting images of food. There are billboards, commercials, and signs everywhere advertising food. Fortunately for drug addicts, the cues associated with drug use are less commonly seen.
There are also negative social consequences associated with using drugs that are not seen when people abuse food. You can be arrested, fined and jailed for buying, selling, and carrying some drugs. You can even be arrested for having certain drugs of abuse that are legal in your car (e.g., an open container of alcohol). There is a social stigma associated with drug use, which is not the case with food. People are usually lauded for showing up with food (think about the last time someone showed up at a party with a plate of brownies, or brought doughnuts into work).
Comparisons between drugs and food have led researchers to look at studies of “food addiction” as a way to understand why there has been such a sharp rise in the obesity rates over the last several decades. The fact that people across the globe are gaining weight rapidly cannot be fully explained by genetic factors or some sort of evolutionary change, as these types of changes don’t happen that quickly. Instead, many suspect that the increase in obesity is due to an environmental change. Our modern-day food environment is filled with opportunities to get quick and easy access to food, which can be a good thing, but unfortunately these convenience foods tend to be highly-processed, dense in calories, and high in sugars. The ease and convenience of such foods lure us to eat them or feed them to our families, but when they are consumed in excess, body weight increases occur.
Research supports the idea that numerous overlaps exist between drug addiction and obesity, both in terms of behavior and brain changes. For example, studies show that when obese people are shown images of foods they desire, their dopamine system is activated as if one were showing drug stimuli to a drug addict. It doesn’t take scientific studies to tell us this; anyone who is overweight and has gone on a diet in an attempt to lose weight can relate to the compulsion and desire to eat certain foods. That is one reason why adherence to diets is so poor: people find it almost impossible to give up the foods that they love (which are usually high in calories and contain a lot of sugars).
So when it’s proposed that certain foods with a high concentration of sugar or fast-digesting carbs in them may be addictive, what does this mean? Obviously humans crave food because we need it to survive, but simply craving sugary, high-carb foods does not mean that we are addicted to them. Humans, especially when very thirsty, crave water, but nobody would claim that anyone has an addiction to water. If you left a person in the desert long enough and offered them water or even just showed them pictures of water, you would probably see a release of dopamine in their brain. Exhibiting this response is not sufficient to say that something is addictive. Addiction is something fundamentally different. How does one cross the line from user to abuser to addict?
Lots of people try drugs. In the U.S., for example, approximately 50% of adults consume alcohol occasionally. However, only approximately 5% of U.S. adults have been reported to have alcohol abuse. The same pattern is seen for other types of drugs: many may try, but few become addicts. So what is different about food? We are all users of food, and most of us have abused it at one time or another (think about Thanksgiving dinners in your past). But how many people are actually addicted?
There are relatively few drug addicts out there; should we expect the same for food addicts? Probably not. Recent studies suggest that up to 11.4% of normal-weight people may meet the criteria for a diagnosis of food addiction. The numbers are higher among binge-eating disorder patients (up to 40.5% of individuals can be classified as food addicts) and obese patients (up to 57%). These statistics seem extremely high especially when considering that rates of alcoholism fall between 2-8%, but think about this: If drugs of abuse were legal, easily accessible, highly visible, socially accepted, and everyone used them all of the time (as is the case with palatable foods), I bet there would be a lot more people addicted to drugs, too.
Dr. Nicole Avena is a research neuroscientist/psychologist and expert in the fields of nutrition, diet and addiction. She has published over 50 scholarly journal articles, as well as several book chapters on topics related to food, addiction, obesity and eating disorders. She recently edited the book, Animal Models of Eating Disorders (Springer/Humana Press, 2013), and she has a book Why Diets Fail (Ten Speed/Crown) forthcoming in 2014. Her research achievements have been honored by awards from several groups including the New York Academy of Sciences, the American Psychological Association, the National Institute on Drug Abuse, and her research has been funded by the National Institutes of Health (NIH) and National Eating Disorders Association.