Related Experiment Video
Updated: Jul 24, 2026

Studying Food Reward and Motivation in Humans
Published on: March 19, 2014
Differential effects of d-fenfluramine, l-fenfluramine and d-amphetamine on the microstructure of human eating
J. McGuirk1, E. Goodall, T. Silverstone
1Academic Unit of Human Psychopharmacology, Medical College of St Bartholomew's Hospital, London EC1 7BE, UK Department of Psychology, City of London Polytechnic, Old Castle St, London E1 7NT, UK.
Abstract:
An observational technique, demonstrated to provide reliable data under a variety of conditions, was used to evaluate the effects of d-fenfluramine, l-fenfluramine, d-amphetamine, and fenfluramine-amphetamine combinations on eating behaviour in human subjects. Following an overnight fast, subjects ate lunch from a dispenser allowing free access to a choice of ten sweet and savoury foods, of varying macronutrient composition. D-fenfluramine (30mg) and d-amphetamine (15mg) reduced food intake; l-fenfluramine (30mg) was essentially inactive. The net effects of d-fenfluramine and d-amphetamine on food intake were additive, but the behavioural mechanisms of action were different for the two drugs. D-amphetamine decreased the duration of the meal, as well as the time spent chewing or manipulating food and the number of bites, but had no effect on eating rate; by contrast, d-fenfluramine decreased the rate of eating, but had no effect on meal duration.
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