Tuesday, October 27, 2009

Weighing In on 'Conditioned Hypereating'

By: Lisa J. Merlo, Ph.D., and Mark S. Gold, M.D.

Author and former Food and Drug Administration Commissioner David A. Kessler presents a provocative theory of why we overeat, complete with sound (though somewhat limited) science, a pair of addiction researchers write in this review.

“[That] is a load of fat on fat on fat and sugar that’s then layered with fat on sugar on sugar and served with fat, salt, and fat. . . .”   (pp. 86–87)

As unappetizing as it sounds, this is author David A. Kessler’s striking way of describing a special dish at a popular chain restaurant, where sugar, fat and salt are purportedly combined in exacting proportions to create what one food industry executive calls “craveability.” In The End of Overeating: Taking Control of the Insatiable American Appetite, Kessler further quotes this executive to illustrate how companies throughout the food industry engineer their products “to get you hooked” (p. 125). Kessler, former commissioner of the U.S. Food and Drug Administration, used to lead the fight against Big Tobacco. Now he has turned his attention to Big Food.

Although it remains unclear to what extent food industry executives understand the physiological and neurobiological impact of highly processed foods on consumers, it is obvious that they have uncovered the formula for creating mass-market products that stimulate repeated consumption. In his book, Kessler explores how the omnipresence of “hyperpalatable” foods in American society has given them increasing salience in our lives. It is difficult for many of us to ignore the siren call of the doughnut tray in the break room, the co-worker’s candy dish, the drive-through restaurants on the way home or the bowl of ice cream we enjoy while watching the nightly news. Kessler argues that this “conditioned hypereating,” the drive to eat beyond our needs, contributes to the global obesity epidemic and its innumerable consequences for our health.

The End of Overeating follows Kessler’s quest to understand why so many people—including Kessler himself—lose control in the presence of food. In describing his plight, Kessler compares overeating to both pathological gambling and substance abuse. He writes that “it becomes an automatic response to widely available food and its cues, [and it is] excessive, driven by motivational forces we find difficult to control” (p. 145). Research supports Kessler’s argument: The discovery that drugs assert their control over the brain by “hijacking” the neurobiological reward circuitry, rather than by merely producing withdrawal states, expanded the pool of potential substances of abuse to include food. Kessler suggests that because drugs, sex and food all affect the level of the neurotransmitter dopamine in the nucleus accumbens (the reward center of the brain), we may perceive foods that are hyperpalatable as more rewarding than those that are nutritious, thus increasing the likelihood that we will abuse the former.

The book is divided into six sections; the first three introduce concepts related to food production and marketing and how these processes influence our brains. Kessler describes how foods can become highly reinforcing stimuli as a result of neurobiological reward processes and environmental and social cues. For example, he presents the concept of “neuronal encoding” for palatability, where brain cells respond to rewarding foods and release electrochemical signals to stimulate other brain cells, and illustrates it with studies demonstrating that an animal will work almost as hard for a high-sugar, high-fat food as it will for cocaine. He discusses orosensory self-stimulation, which occurs when the ingestion of highly palatable foods stimulates the brain’s natural opioid receptors, thereby encouraging the brain to crave more of these foods. In addition, Kessler reviews research that has shown how conditioning can increase cravings for certain foods.

This material prepares the reader for sections four and five, which discuss the theory and framework of “food rehab,” strategies to curb addictive appetite and restore healthy eating habits. Though this book is not intended to serve as a diet manual, it does offer useful suggestions for controlling eating habits.

In the final section of the book, Kessler argues that policy changes requiring the food industry to adopt more-responsible practices could better safeguard the public from reinforced overeating. Kessler contends that improved regulation might help people recover from conditioned hypereating in the United States, much as tobacco regulations have curtailed smoking.

A quick read at 320 pages, this provocative volume stimulates the reader’s desire for answers about the allure of hyperpalatable foods. The author’s personal experiences and those of his acquaintances add color and context to Kessler’s theory, and the concepts remain clear and relevant. Kessler supports his anecdotes with applicable research not only from brain-related disciplines such as psychology, neuroscience and psychiatry, but also from the fields of nutrition, medicine, culinary arts and marketing. He quotes material from personal interviews with the researchers in addition to reviewing and referencing scientific journal articles and textbooks.

In addition, Kessler focuses on broad concepts such as conditioning, reward, craving and addiction instead of following obscure, late-breaking discoveries involving specific genes, hormones or neurotransmitters. This approach makes the information more accessible to readers outside the field of neuroscience and prevents the book from becoming out-of-date almost immediately. Finally, Kessler provides 52 pages of endnotes that include both additional details and references for the research studies and interviews highlighted in the text. The comprehensive index also adds value; it lists material in the endnotes as well as in the main text.

Kessler could not cover everything in a relatively short volume, and some omissions will be particularly apparent to readers interested in neuroscience. For example, there is no discussion of the cutting-edge work of Kelly Brownell and his colleagues at the Rudd Center for Food Policy and Obesity at Yale University, who have examined how public health interventions, such as junk food taxes and nutrition labeling, affect the spread of obesity.1 Second, Kessler introduces the term conditioned hypereating but does not refer to literature that explores the related concept of food addiction. First introduced in 1956,2 food addiction has been covered rather extensively in the past decade.

Kessler also could have included elements of research that apply to his theory of conditioned hypereating, such as those covered in a special issue of the Journal of Addiction Medicine that I (Gold) edited earlier this year.3 For example, Kessler seems not to have recognized the support for his theory in the accumulating imaging results, which Gene-Jack Wang of the Brookhaven National Laboratory published in a review describing how neuroimaging of brain dopamine pathways relates to obesity.4 Moreover, Kessler should have discussed not just in the endnotes but in the text of his book the innovative animal studies by Bart Hoebel and colleagues at Princeton University,5 who examined sugar addiction in rats. Next, Kessler ought to have included recent work implicating high-fructose corn syrup in the many negative health effects of obesity and overeating. For example, reference to the work of Richard J. Johnson of the University of Colorado Health Sciences Center, who wrote The Sugar Fix in 2008, would have strengthened Kessler’s book.

Finally, given Kessler’s heavy reliance on primary sources’ personal experiences, it is curious that he did not include at least one interview with someone who had undergone bariatric surgery or lap-band surgery. Because they often experience a drastic shift in their relationship with food, these individuals would have provided a unique perspective on Kessler’s theory.

But these omissions do not detract from the fascinating nature of the book or its potential impact on public health. On the whole, The End of Overeating is thought-provoking and soundly based in science. It also provides some preliminary suggestions for conquering conditioned hypereating. Be forewarned: After digesting this volume, you might not be able to look at food in the same way. You might find yourself critiquing the descriptions of entrées on restaurant menus, studying food labels and discarding some of your former favorite foods. Kessler would approve of such behaviors because they would contribute to a “critical perceptual shift” (p. 234) in public opinion toward food. This shift will be necessary for American society to overcome the epidemic of conditioned hypereating.


1.     M. B. Schwartz and K. D. Brownell, “Action Necessary to Prevent Childhood Obesity: Creating the Climate for Change,” Journal of Law and Medical Ethics 35, no. 1 (2007): 78–89.

2.      T. G. Randolph, “The Descriptive Features of Food Addiction: Addictive Eating and Drinking,” Quarterly Journal of Studies of Alcohol 17, no. 2 (1956): 198–224.

3.     M. S. Gold, N. A. Graham, J. A. Cocores, and S. J. Nixon, “Food Addiction?” Journal of Addiction Medicine 3, no. 1 (2009): 42–45.

4.     G. J. Wang, N. D. Volkow, P. K. Thanos, and J. S. Fowler, “Imaging of Brain Dopamine Pathways: Implications for Understanding Obesity,” Journal of Addiction Medicine 3, no. 1 (2009): 8–18.

5.     B. G. Hoebel, N. M. Avena, M. E. Bocarsly, and P. Rada, “Natural Addiction: A Behavioral and Circuit Model Based on Sugar Addiction in Rats,” Journal of Addiction Medicine 3, no. 1 (2009): 33–41.

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Bill Glovin, editor
Carolyn Asbury, Ph.D., consultant

Scientific Advisory Board
Joseph T. Coyle, M.D., Harvard Medical School
Pierre J. Magistretti, M.D., Ph.D., University of Lausanne Medical School and Hospital
Helen Mayberg, M.D., Icahn School of Medicine at Mount Sinai 
Bruce S. McEwen, Ph.D., The Rockefeller University
Donald Price, M.D., The Johns Hopkins University School of Medicine
Charles Zorumski, M.D., Washington University School of Medicine

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