Effects of initial body weight on anorexia and tolerance to fenfluramine in rats.

The initial anorexia and development of tolerance to dl-fenfluramine was examined in rats with graded pretreatment body weight losses. Fenfluramine strongly attenuated food intake on the first test day in all weight groups and the magnitude of the initial anorexia did not differ between groups. The time course of anorectic tolerance was also similar in each of the groups. The results do not support a strict "set point" hypothesis according to which the tolerance to fenfluramine anorexia is an artifact of decreasing body weight and/or concurrently increasing relative food deprivation.