[External stimulus dependence in food intake of obese adolescents: studies using a food dispenser]

According to the theories of Schachter concerning the external response of obese adults, which have been confirmed by Jung, Pudel and Nisbett, we tested these theories in obese adolescents. Eating behaviour of 16 grossly obese adolescents (8 males, 8 females, mean age 13.2 +/- 0.3 years, mean relative body weight 124 +/- 2%; mean +/- SD) and 16 normal weight age-matched adolescents (8 males, 8 females, mean age 13.4 +/- 0.2 years, mean relative body weight 97 +/- 3%) were investigated under four different test situations. 1. drinking test with vanilla-mix (790 kcal/l) 2. drinking test with vanilla-mix (1090 kcal/l) 3. drinking test with visual illusion 4. drinking test during a stress situation No significant differences were found between obese and normal weight concerning the absolute amounts of vanilla-mix consumed nor in total energy intake. However, differences in test 1, 3, and 4 concerning the amounts estimated prior and after the tests. Compared with the first drinking test in test 2, 3, and 4 the obese probands consumed significantly more vanilla-mix and total calories than the lean. In bicycle-ergometry the obese revealed significantly lower exercise values (p less than 0.02) than the normal weight probands. Furthermore, the obese adolescents showed a massive discrepancy between the subjective working ability and the objective measurement of the individual pulse rate. In our tests we could demonstrate that obese adolescents are more sensitive to external stimuli than normal weight. The theory of higher responsiveness of obese to external stimuli therefore is also valid for obese adolescents.