Food Addiction: Cheesecake-Eating Rats and Obesity as a Mental Illness
Food Addiction: Cheesecake-Eating Rats and Obesity as a Mental Illness
By: Michele R. Berman, MD | October 12, 2010
In a 2007 Editorial in the American Journal of Psychiatry, Dr. Nora Volkow, director of the U.S. National Center on Drug Abuse (NIDA), asked if obesity should be included as a brain disorder in the upcoming Diagnostic and Statistical Manual of Mental Disorders (DSM-5, expected in 2012). She posed this question based on mounting evidence that foods can trigger behavioral and physiological processes that are similar to or overlapping with those caused by classic drugs of abuse.
The published evidence for food addiction is derived from both animal models and human studies using a wide range of experimental approaches including genetics, neuroendocrinology, neuroimaging studies, and behavioral models (see selected bibliography). For example, using behavioral models borrowed from drug-addiction research, one group examined "cheesecake-eating" rats who were given access to not cocaine or heroin but rather a "cafeteria-style" diet including bacon, sausage, cheesecake, pound cake, frosting and chocolate.
The rats showed disruptions in brain reward function similar to those that occur following administration of addictive drugs. The rats also demonstrated a behavioral effect, insensitivity to adverse consequences of food administration (compulsiveness), that is considered a hallmark of addiction in humans.
Turning to humans, Ashley Gearhardt and colleagues at Yale University recently reviewed the literature and found substantial evidence that some people lose control over their food consumption and display other behaviors (e.g. tolerance, withdrawal) that may fulfill DSM-IV-TR diagnostic criteria for substance dependence. They also discuss food addiction in the context of lessons learned from the different histories of alcohol and nicotine dependence and note that all addictions are not treated in the same way with regard to personal responsibility, culpability of companies that produce products for consumption, and the implications for public policy.
Gearhardt and colleagues have developed and tested a psychometric measurement tool, the Yale Food Addiction Scale (YFAS), to identify eating patterns and types of foods in ways that should facilitate further research aimed at evaluating the similarities between addiction to psychoactive substances and excessive food consumption. (Gearhardt's May 13, 2010 lecture on UCTV)
As Gary Taubes describes in his new book Why We Get Fat, psychologists and psychiatrists "took over" obesity in the 1960s (from its pre-war research home in the fields of nutrition, metabolism, endocrinology and genetics) and made it "an eating disorder -- a character defect, but in kinder words..." Even today, it's not hard to find mass market diet books authored by the likes of psychologist "Dr. Phil" McGraw and even the daughter of the founder of cognitive-behavioral therapy, Dr. Judith Beck who provides this approach to obesity: "Train Your Brain to Think Like a Thin Person."
So are psychiatrists and psychologists ready to assert themselves again, formally defining obesity as a brain disorder in the second decade of the 21st century? Apparently not: last May the American Psychiatric Association rejected obesity as a psychiatric diagnosis for inclusion in DSM-5. Dr. Volkow will have to wait perhaps another 10-15 years for the issue to be reconsidered.
In the meantime:
"Obese people, who are already subject to adverse health effects, are additionally victimized by a social stigma predicated on the Hippocratic nostrum that weight can be controlled by 'deciding' to eat less and exercise more. This simplistic notion is at odds with substantial scientific evidence illuminating a precise and powerful biologic system that maintains body weight within a relatively narrow range. Voluntary efforts to reduce weight are resisted by potent compensatory biologic responses. Further progress in understanding and treating obesity will come not from repetition of anachronistic preconceptions but rather from the rigorous scientific approach that has driven advances in so many other areas of medicine." -- Dr. Jeffrey M. Friedman, Howard Hughes Medical Institute and Rockefeller University (discoverer of the "obese gene" encoding the neuroendocrine hormone, leptin)
Lastly, what do you suppose is the addictive substance in food for which there is the most scientific evidence? Sugar.
Note: You may want to suggest to dieting patients who have trouble with typical food journaling that they try PhotoCalorie. It's an iPhone app that lets you take a picture of a meal or snack and enter a short description and it will estimate the calorie and nutritional content and produce daily summaries of the calories and nutrients consumed.