It’s certainly tempting to think of some foods as being addictive. Buttered popcorn and doughnuts with sprinkles come to mind. These highly palatable, sugar- and fat-stuffed goodies are clearly “junk foods,” but does unrestrained splurging on them really a food junkie make?
An Internet search would lead you to believe so—not only that “food addiction” is real, but also in offering ways to recognize signs and symptoms, take self-diagnosis “quizzes”, and going as far as giving advice on treatment of our sugar- and fat-hijacked brains and their dopamine-reward systems.
“When you google ‘food addiction,’ Fox News gives you not one but seven ways to beat it,” said James Hill, professor of pediatrics and medicine at the University of Colorado’s Anschutz Medical Campus, in a symposium on Monday, April 28, in San Diego at Experimental Biology. “The concept of food addiction is becoming widely accepted, but a critical evaluation is needed.”
In a earlier interview with ASN, the session’s co-chair Michael Kelley, Senior Principal Scientist for the Wm. Wrigley Jr. Company, said that the goal of the RIS was to have a comprehensive session that evaluated “where we stand” on the issues such as terminology used, mechanism of action, methodologies, and outcome measures. “Central to the review will be questions of what current technologies tell us, what they are not capable of telling us, and where we should go from there,” he said.
The symposium took place at the American Society for Nutrition (ASN) Scientific Sessions and Annual Meeting. ASN’s Nutrition Translation Research Interest Section (RIS) organized the session in collaboration with ILSI NA.
The evidence for food addiction
Providing some support for the food addiction model are studies in animals, some functional magnetic resonance imaging (fMRI) studies, and studies that have used the Yale Food Addiction Scale that was created through applying the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria.
Calling the food addiction model “conceivable” is neuroscientist Kent Berridge, of University of Michigan, who studies how the brain reacts to sensory pleasures. He does this through a series of animal experiments using drug microinjections and lasers, including comparing facial expressions of (cute!) rats and human babies in response to bitter and sweet.
Using these techniques, Berridge’s lab has been able to map “hedonic hotspots” in the brain, where patterns of firing neurons signal a ‘liking’ response to sensory pleasure such as to that of sweetness. “The brain sees a difference between ‘liking’ and ‘wanting’,” he said. And it’s a major difference. “‘Liking’ for food exists, but the brain system for ‘wanting’ is much larger, more robust, and complex.”
The more intense ‘wanting’ of a reward, or what Berridge calls incentive salience, is of a psychological nature, for example, and doesn’t have to necessarily provide sensory pleasure. This may be because unlike pleasure ‘liking’, reward ‘wanting is driven by dopamine.
Berridge also highlighted the work of Brookhaven National Lab’s Dr. Gene-Jack Wang and colleagues who showed that dopamine reward circuitry in the brains of obese binge eaters and drug addicts had some similarities. For example, obese binge eaters have a higher dopamine release in their brains in response to food cues.
Research neurologist Nicole Avena, of Columbia University’s New York Obesity Research Center, said these food cues are all around us in our modern environment in the form of highly palatable foods rich in sugars and fats that taste good. It’s “hedonic eating” versus eating to gain calories to survive. “People eat because they want to eat, not because they have to eat. They eat because they’re bored or stressed,” she said.
That doesn’t necessarily mean we’re all addicted, but that some foods can lead to addictive-like behaviors.
Providing some support for the food addiction model are studies in sugar-bingeing rats from Avena’s lab. She said that they found that while increases in dopamine tend to fade in response to their regular chow, the opposite happens with exposure to sugar. The dopamine release rises. A similar effect was also seen in response to fat by another lab. “When we give rats sugar, they overeat the sugar. They will also develop a pattern where they consume more and more in a month,” she said.
Those sugar-bingeing rats also work harder to get to cues associated with eating more sugar, even if it means getting shocked with electricity. They are also more likely to consume alcohol and show signs of anxiety withdrawal symptoms, she said.
Although there is little evidence of humans having withdrawal symptoms in response to sugar or fat, Avena said, the work of Yale psychologist Ashley Gearhardt and colleagues have evaluated neural correlates of addiction through fMRI images. In addition, they created the Yale Food Addiction Scale and have used it in studies to identify those with possible food addiction-like disorders.
The evidence against food addiction
Unconvinced of the validity of the Yale Food Addiction Scale, however, was psychiatrist Hisham Ziauddeen, of the University of Cambridge. Reminding that the DSM-IV was designed specifically for abuse of substances such as drugs that lead to tolerance and withdrawal, he said, “The DSM-IV criteria was never set up for a substance that you need.”
Ziauddeen also said that the evidence from the rat-brain studies and brain imaging scans weren’t very useful for obesity. The animal models don’t translate well to humans, for example, and the clinical overlap is unconvincing. By the same logic one could argue that water was addictive because it acted in the same neurons as cocaine.
In addition, the classification for considering which foods would be addictive and not is too “broad and imprecise”. “Consider the problems,” he said. What would be regulated or implemented? Would cheesecake be illegal? Or, how would cheesecake be available from one population but restricted from another?
Neurologist Dr. Miguel Alonso-Alonso, of Harvard University, dug deeper into the problems with using fMRI studies to support the food addiction model. “Money, sex, and art activate the same regions,” he said.
There are also differences in the way food activates the brain versus drugs. There are even differences depending on, say, one peels an apple in a real-life setting versus in an fMRI setting. There’s also a problem of treatment. What would it be? “From diet studies, we already know that abstinence diets or rigid restriction diets are likely to fail,” he said.
What is likely a better strategy, Alonso-Alonso said are interventions targeting “cognitive control” (e.g. physical activity, mindfulness) to promote healthy eating and maintaining a healthy weight.
Closing out the symposium, biostatistician David Allison of University of Alabama offered his thoughts on how to move forward on neurocognition research. He warned against being “blinded” by a new technology like brain imaging that can appear “fascinating and cool” To be valuable and valid, he said, there needs to be meaningful questions, valid designs, proper analyzation of the data, and proper interpretation of results. “If we want to know if X exists, then we have to define what X is,” Allison said. “It’s important to have clear criteria. What is ‘food addiction’? How do we do research well?”
Mostly what we need is “sound thinking,” Allison said. One example of sound thinking about fMRIs and food addiction, he said, is found in an article written by Yale Prevention Research Center’s own Dr. David Katz:
“… a paper by Gearhardt and colleagues in the Archives of General Psychiatry shows that those individuals scoring higher on a scale for “food addiction” have more intense responses in the reward circuitry of the brain, revealed using functional MRI scans, than counterparts scoring lower.
The media attention this study has generated would suggest that it delivers an epiphany. But I think the case is just as strong that it delivers a tautology: those who report receiving a stronger, more irresistible reward message from their brain in response to food have a stronger, more irresistible reward response in their brain in response to food.
With or without brain scans, we knew that food affects the brain.”
Evolving Health 
“Would cheesecake be illegal?” Alcohol is addictive but not illegal. The addiction model will be a great help in ending junk food marketing targeted to children.
Hi David,
Nice post. It is a complex issue with no definitive answers yet. Part of the problem is that addiction is a difficult thing to define and the definitions in use remain fuzzy and controversial. At its heart, addiction is an excessive motivation to engage in a reward-seeking behavior, e.g. a drug, gambling, etc. Where do we draw the line between normal reward-motivated behavior and excessive reward-motivated behavior? That’s the tough part. There is no clear line for food, but there is also no clear line for drugs or gambling.
Currently, we say someone is addicted when the pull to engage in the behavior is having a serious negative impact on that person’s life. It’s a very subjective definition but it’s still the best one we have. There will probably never be a useful neurobiological definition of addiction, because fundamentally addiction is defined by behavior. That’s the point I made to Paul Fletcher (Ziauddeen’s co-author) after his talk at the Obesity Society. In my opinion, arguing about whether or not fMRI data supports addiction is missing the point. If someone is stealing TVs to buy crack, who cares what the fMRI says? If someone is leading a normal constructive life with occasional controlled gambling, but his reward centers light up like a Christmas tree when he sees images of a slot machine, is that person an addict? Of course not. The definition of addiction is behavioral.
And so it is with food. At some point, you have to draw an arbitrary line and say that addiction is what lies beyond it. The Yale Food Addiction Scale is currently the best attempt I’m aware of to draw a line that’s based on current definitions of non-food addiction. Whether or not that’s appropriate can be debated, but I think it’s a good start. Some would say “how can you be addicted to a substance you need to consume, like food?”. The key is that we aren’t talking about food in general. We’re talking about specific foods that are highly rewarding, and there is no dietary requirement for those foods just as there is no physical requirement for drugs of abuse. I’ve never heard of an oatmeal or lentil addiction. It’s cake, cookies, chips, candy, and that sort of thing that triggers addiction-like behavior.
In the end, I think food addiction is real, but it doesn’t fully explain obesity. Most people don’t have a relationship with highly rewarding foods that resembles compulsive drug use, but that is certainly debatable. Frankly I think part of the problem here is that if we accept that addiction means engaging in a reward-seeking behavior that’s harmful, it implies that a huge percentage of the general population really is addicted to highly rewarding foods and beverages. People eat these foods because they like them and they’re motivated by them, and those foods are clearly harmful to health, particularly when consumed in excess. But it’s a conclusion that is highly unpalatable for most people!
Your RT of DrugMonkey’s tweet during the event (“Why is it so hard to grasp that *everything* that is reinforcing or pleasurable has the potential to be addicting?”) is, IMO, critically important. Too much addiction study is in the tolerance/withdrawal/disease model, and if that’s what you are looking at, you may be missing what’s going on (like the man looking for his keys under the streetlight).
I am a fan of the works of Stanton Peele and Marc Lewis, both of whom essentially argue that addiction is a developmental issue. Lewis, a former addict turned neuroscience researcher, recently wrote on his blog that his forthcoming book “makes the case that addiction results from accelerated learning — the acquisition of thought patterns that rapidly self-perpetuate because of the brain’s tendency to become sensitized to highly attractive rewards. I see this as a developmental process, accelerated by a neurochemical feedback loop that’s particular to strong attractions.”
I see addiction to food as an endpoint just as it is to gambling or alcohol, other things that many/most people enjoy and sometimes overindulge in without serious harm. But Stephan articulated much better what I was inclined to say, including that it is not likely that a huge percentage of the population is addicted.
BTW, I should have mentioned Carl Hart as another neuroscience researcher doing some fascinating work in addiction at Columbia. His perspective is a bit more like Bruce Alexander’s (of Rat Park fame) in terms of addiction … esp wrt the role of environment including class and race. Well worth a look.
I should clarify that I grasp why we need to find supposedly objective measures that show brain changes identical to those observed with addiction that everyone readily believes. It is highly valuable to continue to make the point that these are disruptions of reward and affect, not drug-specific or stimulus-specific changes that are the common root problem. Accumulating evidence brings more people to the understanding that I have, expressed in that above mentioned twitt.
It can also help to show why addiction is not necessarily dependence (measured by x, y or z) is not necessarily a drug *problem*. this latter can be sticky but it isn’t hard to take a broad view. Illicit and licit drugs have very different implications for the diagnostic criteria that are related to legal complications, life consequences and obtaining the substance. I can be highly dependent on caffeine and yet because modern life offers it up to me cheaply and quickly, at nearly every possible turn, and caffeine intoxication is compatible with my day job it doesn’t pose that great of a drug problem.
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