Dr. Kessler's book focuses on 1) the ability of food with a high palatability/reward value to cause overeating and obesity, 2) the systematic efforts of the food industry to maximize food palatability/reward to increase sales in a competitive market, and 3) what to do about it. He has not only done a lot of reading on the subject, but has also participated directly in food reward research himself, so he has real credibility. The End of Overeating is not the usual diet book.
As you may realize if you've been following this blog for a while, I think food reward is a major determinant of food intake and a contributing factor to obesity. It's great to see a book that tackles the topic in the popular press, making it accessible to nearly anyone.
Dr. Kessler starts out by making the case that sugar, salt and fat cause overeating, and that much of the food industry is based around finding novel ways of packing more of these three ingredients into food to maximize palatability. He repeats an idea that is common in the food reward literature, that reward and pleasure circuits in the brain override circuits that are designed to stabilize body fat stores (body fat homeostasis), establishing a higher 'settling point'. I have a minor quibble with this; my belief is that excessive reward may partially override homeostatic circuitry, but it also re-regulates it to defend body fatness at a higher level (a hypothesis shared by certain other obesity researchers). This may be one of the reasons why overweight/obese people 'defend' a higher fat mass, making weight loss difficult and often destined for failure.
A second problem is that Dr. Kessler didn't do a good job of clearly defining reward and palatability. He seems to confuse palatability with reward at times:
In everyday language, we call food palatable if it has an agreeable taste. But when scientists say a food is palatable, they are referring primarily to its capacity to stimulate the appetite and prompt us to eat more. Palatability does involve taste, of course, but, crucially, it also involves the motivation to pursue that taste. It is the reason we want more.Actually, I believe the first sentence had it right. Palatability is the hedonic, or pleasure value of food. The motivation to pursue food, "the reason we want more", is due to the reward or reinforcing value of the food. As far as I know, those are the accepted scientific definitions, although some people do use the term reward more broadly to include hedonic value*. The two concepts are admittedly easy to confuse, because they overlap and in practice often travel together. I have to believe that Dr. Kessler understands what reward and palatability are, but he does not convey that understanding effectively in the book.
Another quibble I have is that he focuses too persistently on sugar, fat and salt. These are clearly major reward factors, but so are calorie density, certain textures, free glutamate, starch and a few others. In addition, many other cues (particularly flavors) become rewarding as they are associated with those factors. Some of these are mentioned or implied (except starch, a major omission in my opinion), but the book is focused primarily on sugar, fat and salt throughout. I suspect he wanted to keep it simple for clarity's sake, but that decision did sacrifice some amount of completeness.
The book goes into considerable detail about the remarkable science of food engineering by processed food manufacturers. The goal, as one executive bluntly put it for Dr. Kessler, "is to get you hooked", by creating food stimuli that stimulate reward circuits as much as possible. It's a science and an art, where refined ingredients and synthetic flavorings are the palette they use to paint foods. One of the great strengths of the book is the large number of interviews Kessler did with food industry executives-- and the candid information they provided. The End of Overeating is worth the cover price for that alone.
In the latter part of the book, Kessler provides practical advice for fat loss based on the food reward ideas. It mostly revolves around learning how to wean yourself off junk food, using an approach similar to drug rehab strategies. I think there are a lot of useful ideas there, but some people may need a more focused and comprehensive strategy to regain leanness in my opinion.
A final gentle critique is that the book is not very focused or well organized. It often rambles on with long study descriptions, quotes and redundant information. I think it would have been more effective if it were a concise and focused 200 pages (the book was 320). It would have benefited from a thorough and assertive editor.
Overall however, I liked the book. It contains a lot of good information and practical advice from a credible source, and to my knowledge it's the only book focused on food reward in the popular press. I recommend it to anyone who wants to expand their knowledge on food reward, and the manner in which the processed food and restaurant industries employ it. I've added it to my list of recommended books in the sidebar.
Melissa McEwen also commented on The End of Overeating here.
*By this definition, reward has a hedonic (pleasure) component, a motivational component, and a learning component. Researchers sometimes call the motivational and hedonic elements "wanting" and "liking", respectively (1). I may switch to this definition at some point, because it's widely accepted and easier than saying "reward" and "palatability" separately every time I want to mention these ideas.