increased lipolysis has been suggested as one of the possible mechanisms underlying cancer cachexia, The study aim was to assess whether lipolysis is increased in weight-losing cancer patients, considering their differences in food intake and body composition. Sixteen healthy subjects and 18 cancer patients with different tumor types and a weight loss of at least 5% in the previous 6 months were included in the study. Food intake was recorded for 4 days. After an overnight fast, [1,1,2,3,3-H-2(5)]glycerol was infused to determine the rate of appearance (Ra) of glycerol as a measure of whole-body lipolysis, and [1-C-13]palmitic acid was infused to determine the Pa of palmitate as a measure of adipocyte fatty acid release, Palmitate oxidation was determined by measuring (CO2)-C-13 enrichment in breath samples, and body composition was measured by bioelectrical impedance analysis, After adjustment for energy intake, whore-body lipolysis was significantly higher in cancer patients versus healthy subjects (6.46 +/- 0.63 and 4.67 +/- 0.46 (mu mol/kg +/- min, respectively, P <.05). The difference in adipocyte fatty acid release did not reach statistical significance. The rate of palmitate oxidation was also significantly higher in patients than in healthy subjects (1.15 +/- 0.10 and 0.93 +/- 0.07 mu mol/kg . min, respectively, P <.05). No differences in body composition were observed between groups. In conclusion, whole-body lipolysis las measured by the Pa of glycerol) and palmitate oxidation were elevated in weight-losing cancer patients, but fatty acid release was not significantly different. by W.B. Saunders Company.