1. Seventeen male subjects with an energy intake of 10.6 (sd 1.7) MJ/d and ten male undernourished labourers with an energy intake of 8.0 (sd 1.2) MJ/d were studied. The controls were subdivided into ten underweight controls with a body mass index (weight/height2; BMI) < 18 (17.2 (sd 0.9)) and seven normal-weight controls with a BMI > 20 (21.3 (sd 1.6)), while the undernourished labourers had a BMI < 18 (16.8 (sd 1.2)).
2. Comparison of thermogenic responses to increasing doses of noradrenaline showed no overall significant inter-group differences when subjected to a nested analysis of variance (ANOVA). For the initial doses of 0.05 and 0.1 μg noradrenaline, significantly lower responses were seen in the undernourished subjects, while the highest dose showed comparable responses in all three groups. Thermogenic responses to the initial two doses, when corrected for fat-free mass (FFM) differences, were 40 % lower in the undernourished group when compared with the underweight group with similar BMI and FFM values. However, this finding was not statistically significant.
3. The basal oxygen consumption of the undernourished group, expressed per unit FFM, was significantly higher than that of the controls.