Friday, September 2, 2011

Reward does a book review

Quotes follow;

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.

                        perhaps we should add grains   v
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 does not override homeostatic circuits, but re-regulates them to defend body fatness at a higher level. This is why overweight/obese people essentially mount a starvation response when they try to lose fat by deliberately restricting calories, making the process difficult and often destined for failure.

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.

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*.

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.

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.

By this definition, reward has a hedonic (pleasure) component and a motivational component. Researchers sometimes call these "wanting" and "liking" (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.

"It's very important that we emphasise this: eating has to be pleasurable, it has to be rewarding"
"...if anything you need to focus on foods you like MORE than the fat, sugar and salt."

end of quotes

I think they got it.  Book is likely worth a read.

I also think grain, a sugar, after enzymes get to it should be specifically named. Salt is required and speeds the absorption of glucose in the gut wall. The salt in the product increases the speed of absorption.  

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