Postprandial thermogenesis in leanness and anorexia nervosa.

Resting energy expenditure (REE) and postprandial thermogenesis (PPT) after the ingestion of a mixed test meal (3.56 MJ, 850 kcal) were determined in 7 anorectic patients, 7 very lean women and 8 control women. REE is absolute value was sharply decreased in the anorectics, but did not significantly differ between the very lean and the control subjects. On the other hand, when adjusted for body weight, REE only tended (p = 0.18) to be lower in the anorectics in comparison to the control women. PPT was similar in the anorectics (187.2 +/- 24.6 kJ/4 h) and the controls (200.7 +/- 16.8 kJ/4 h), but lower in the lean subjects (137.5 +/- 20.0 kJ/4h: p less than 0.05) than in the other two groups. The present study shows that the thermic response to the ingestion of a mixed test meal was not decreased in undernourished anorectic patients whereas it was significantly reduced in very lean healthy women.