Eating behavior in Prader-Willi syndrome, normal weight, and obese control groups

Hyperphagia in Prader-Willi syndrome (PWS) is hypothesized to be due to hypothalamic dysfunction; thus the study of individuals with PWS might illustrate how hypothalamic dysfunction affects eating behavior. The aim of this study was to document the microstructure of the eating behavior in patients with PWS and to compare it with that of members of obese and normal weight control groups of the same age.

Nine subjects with PWS (age, 10 +/- 4 years), 20 normal weight subjects (age, 12 +/- 3 years), and 20 obese subjects (age, 12 +/- 4 years) were served an excess lunch meal (hash) on a hidden scale built into a table and connected to a computer. The plate of food is placed on top of the scale, and when the food is eaten, the change in food weight is registered continuously. An eating curve is displayed online. After the meal, the eating data are fitted to a polynomial, and the computer calculates the amount of food eaten, time of consumption, eating rate (initial and total), and rate of deceleration.

Subjects with PWS were found to have a longer duration of eating (P =.04) and a slower initial eating rate (P =. 01) compared with members of both obese and normal weight groups. In subjects with PWS, 56% of the eating curves were non-decelerating (linear or accelerating) compared with 10% of the normal weight group and 30% of the obese group (P =.02).

The microstructure of the eating behavior in subjects with PWS differs from that of members of obese and normal weight control groups. Thus the eating behavior found in subjects with PWS might be due to decreased satiation rather than increased hunger.