On The Applied Side Activity Anorexia And The Interrelations Between Eating And Physical Activity

In 1967, Carl Cheney (who was then at Eastern Washington State University) ran across a paper (Routtenberg & Kuznesof, 1967) that reported self-starvation in laboratory rats. Cheney (author of this textbook) thought this was an unusual effect, since most animals are reluctant to kill themselves for any reason. Because of this, he decided to replicate the experiment, and he recruited Frank Epling (former author of this textbook), an undergraduate student at the time, to help run the research. The experiment was relatively simple. Cheney and Epling (1968) placed a few rats in running wheels and fed them for 1 hr each day. The researchers recorded the daily number of wheel turns, the weight of the rat, and the amount of food eaten. Surprisingly, the rats ran more and more, ate less and less, lost weight, and, if allowed to continue in the experiment, died of starvation. Importantly, the rats were not required to run, and they had plenty to eat, but they stopped eating and ran as much as 10 miles a day.

Twelve years later, Frank Epling (who was then an assistant professor of psychology at the University of Alberta) began to do collaborative research with David Pierce (author of this textbook), an assistant professor of sociology at the same university. They wondered if anorexic patients were hyperactive, like the animals in the self-starvation experiments. If they were, it might be possible to develop an animal model of anorexia. Clinical reports indicated that, indeed, many anorexic patients were excessively active. For this reason, Epling and Pierce began to investigate the relationship between wheel running and food intake (Epling & Pierce, 1988; Epling, Pierce, & Stefan, 1983; Pierce & Epling, 1991). The basic findings are that physical activity decreases food intake and that decreased food intake increases activity. Epling and Pierce call this feedback loop activity anorexia and argue that a similar cycle occurs in anorexic patients (see Epling & Pierce, 1992).

This analysis of eating and exercise suggests that these activities are interrelated. Depriving an animal of food should increase the reinforcing value of exercise. Rats that are required to press a lever in order to run on a wheel should work harder for wheel access when they are deprived of food. Additionally, engaging in exercise should reduce the reinforcing value of food. Rats that are required to press a lever for food pellets should not work as hard for food following a day of exercise. Pierce, Epling, and Doug Boer, a graduate student, designed two experiments to test these ideas (Pierce, Epling, & Boer, 1986).

Breaking Bulimia

Breaking Bulimia

We have all been there: turning to the refrigerator if feeling lonely or bored or indulging in seconds or thirds if strained. But if you suffer from bulimia, the from time to time urge to overeat is more like an obsession.

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