The answer appears to be the link between glucose levels and the areas of the brain involved with addiction. The speed at which sugar and fat can be absorbed in the system can trigger a quick release of happy hormones. Pizza ranked highest on the list due to the combination of fats and carbohydrates contained in the popular food.
Some magazines have gone so far as to claim “Cheese is the new crack .” However, the study did not give clear comparisons between the illegal drug and the dairy product. If that metaphor were to be true, it would perhaps be better applied to pizza and chocolate. However, cheese did round out the top ten addictive foods list according to the study.
Numerous animal studies have shown that drugs of abuse increase levels of dopamine in parts of the brain, activating the reward system . This is what we see mimicked in food addiction. The problem of obesity is an epidemic that’s plaguing the Western World and showing no signs of easing.
It’s a problem that truly shouldn’t be understated. “An estimated 400,000 adult deaths each year in the United States are associated with obesity. Total costs, which include medical costs and days lost from work because of illness, disability or premature death, from obesity in 2000 were estimated to be $117 billion .”
So how does food addiction happen? According to the authors of the food addiction study, the problem lies not in the natural state of the substance, but rather in the processing. Addictive substances rarely occur in their natural state. However, there are certain things that can be altered or processed in a manner that increases the abuse potential of a particular substance. Grapes, when processed, become wine. Poppies, when processed, become opium. The grape would be far less likely to become addictive. Likewise, the poppy isn’t addictive in its natural state.
That’s the liquor and illicit drug example. But unfortunately, a similar process may be occurring within our food supply due to the amount of highly processed foods lining our supermarket shelves.
“There are naturally occurring foods that contain sugar (e.g., fruits) or foods that naturally contain fat (e.g., nuts). Notably, sugar (or refined carbohydrates) and fat rarely occur in the same food naturally, but many palatable foods have been processed to have artificially elevated quantities of both (e.g. cake, pizza, chocolate). Further, in our modern food environment, there has been a steep increase in the availability of what is often referred to as “highly processed foods”, or foods that are engineered in a way that increases the amount of refined carbohydrates (i.e., sugar, white flour) and/or fat in the food .”
The authors theorize that the addictive potential of a particular food is likely to go up if the food is highly processed enough to actually increase the amount of sugar, fat or refined carbohydrates contained within a particular food substance, especially if the refined carbohydrates hit the blood stream more quickly. According to the study, this is the literal recipe for disaster in the form of food addiction .
“In substance-use disorders, one result of processing addictive substances is often a higher concentration of the addictive agent. An increased potency, or concentrated dose, of an addictive agent increases the abuse potential of the substance. For example, water has little, if any, abuse potential, whereas beer (which contains on average 5% ethanol) is more likely to be abused. In contrast, hard liquor contains a higher dose of ethanol (between 20–75%) and is more likely to be related to problematic use than beer. Similarly, the addition of fat and refined carbohydrates (like sugar) into highly processed foods may increase the “dose” of these ingredients, beyond what one might find in a natural food (such as in fruit or nuts). Increasing the “dose” of these ingredients may elevate the abuse potential of these foods in a manner akin to traditionally addictive substances.”
“Additionally, addictive substances are altered to increase the rate at which the addictive agent is absorbed into the bloodstream. For example, when a coca leaf is chewed, it is considered to have little addictive potential. However, once it is processed into a concentrated dose with rapid delivery into the system, it becomes cocaine, which is highly addictive.”
Once again, research is pointing us back to remarkably simple solutions: eat food that isn’t highly processed. Genius, right? While this may be an easy course of action for some, food addiction is a very real problem for many. In fact, it contributes to many eating disorders – not all of which involve obesity.
“About 50% of the obese, 30% of those overweight, and 20% who are at what are considered a healthy weight, are actually addicted to a specific food, combinations of foods, or a volume of food in general .” Hence, food addiction comes in many different sizes and shapes. Though not all food-addicted people are overweight or obese, it is still far from ideal to be addicted to foods that are artificially high in sugar, fats and refined carbohydrates.
If only we could all be addicted to broccoli and spinach instead! Sadly, we now know pizza and chocolate are far more likely to plague us.
 Schulte, E, Avena, N, Gearhardt, A and Weir, T(Eds) (2015), “Which Foods May Be Addictive? The Roles of Processing, Fat Content and Glycemic Load,” U.S National Library of Medicine, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4334652/ PLoS One. 2015; 10(2): e0117959. 10.1371/journal.pone.0117959 PMCID: PMC4334652, retrieved 6 November
 Harris, J (2015), “Cheese Really Is Crack: Study Reveals Cheese is as Addictive as Drugs,” L.A.Times, retrieved 6 November 2015