Is the obesity epidemic due to the addictive qualities in food or that a lot more food is cheap and plentiful than ever before in history?

A paper presented at the 2013 Canadian Neuroscience Meeting, the annual meeting of the Canadian Association for Neuroscience - Association Canadienne des Neurosciences (CAN-ACN), says the problem is addiction rather than food wealth - the authors claim that high-fructose corn syrup can cause behavioral reactions in rats similar to those produced by drugs of abuse such as cocaine.  It's the "Food Addiction" hypothesis that has recently become popular, which posits that we could be addicted to food just like drugs.  

Addiction happens when drug use shifts from positive reinforcement to the negative kind; drugs are relied on to prevent or relieve negative states that otherwise result from abstinence (e.g., withdrawal) or from adverse environmental circumstances (e.g. stress).

Francesco Leri, Associate Professor of Neuroscience and Applied Cognitive Science at the University of Guelph, suggest food addiction could explain the global obesity epidemic, though binge eaters have greater rates of psychiatric diagnoses involving negative emotional states compared to the general population, so eating may be the symptom and not the cause. The National Institute of Mental Health recently declared an end to support for symptom-based treatment in mental health.

Leri says increased availability of such highly-palatable foods could partly explain the high incidence of obesity around the world, but simple availability does not explain why some people are obese and others are not, given the same amount of available food. Leri, and others have instead suggested individual differences in vulnerability to addiction. Surveys of consumption of cocaine show that though many individuals try these drugs, only a small percentage of them become addicted. Leri set out to show that the same could be true of "addictive foods". "We have evidence in laboratory animals of a shared vulnerability to develop preferences for sweet foods and for cocaine" says Leri. Specifically, Leri wants to prove that high fructose corn syrup (HFCS) is worse for us than table sugar.

Other studies instead say addiction is a disorder of decision-making. 

Leri used rats to examine the behavioral, chemical and neurobiological changes induced by consumption of "addictive foods" containing HFCS. "We are not rats, but our children do not think too much about the impact of sweets on their brain and behaviour. There is now convincing neurobiological and behavioural evidence indicating that addiction to food is possible. Our primary objective is to discover biological predictors of vulnerability to develop excessive consumption of high fructose corn syrup ," says Leri.

John W. Bode, President and C.E.O. of the Corn Refiners Association, said in a statement, “It is irresponsible and ultimately counter-productive for these researchers to associate safe and widely used foods, such as high fructose corn syrup, with illegal narcotics such as cocaine. There remains no credible scientific evidence to suggest that caloric sweeteners, such as sugar and high fructose corn syrup (HFCS), are addictive to humans in general. One of the main weaknesses of the research conducted by Dr. Francesco Leri, like most research seeking to demonize HFCS and other caloric sweeteners, is they are often conducted on animals, such as rats, in scenarios not likely found in the real world experienced by humans."