Lipid metabolism during fasting

Michael D. Jensen, Karin Ekberg, Bernard R. Landau

Research output: Contribution to journalArticlepeer-review

77 Scopus citations


These studies were conducted to understand the relationship between measures of systemic free fatty acid (FFA) reesterification and regional FFA, glycerol, and triglyceride metabolism during fasting. Indirect calorimetry was used to measure fatty acid oxidation in six men after a 60-h fast. Systemic and regional (splanchnic, renal, and leg) FFA ([3H]palmitate) and glycerol ([3H]glycerol) kinetics, as well as splanchnic triglyceride release, were measured. The rate of systemic FFA reesterification was 366±93 μmol/min, which was greater (P<0.05) than splanchnic triglyceride fatty acid output (64±6 μmol/min), a measure of VLDL triglyceride fatty acid export. The majority of glycerol uptake occurred in the splanchnic and renal beds, although some leg glycerol uptake was detected. Systemic FFA release was approximately double that usually present in overnight postabsorptive men, yet the regional FFA release rates were of the same proportions previously observed in overnight postabsorptive men. In conclusion, FFA reesterification at rest during fasting far exceeds splanchnic triglyceride fatty acid output. This indicates that nonhepatic sites of FFA reesterification are important, and that peripheral reesterification of FFA exceeds the rate of simultaneous intracellular triglyceride fatty acid oxidation.

Original languageEnglish (US)
Pages (from-to)E789-E793
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number4 44-4
StatePublished - 2001


  • Free fatty acids
  • Glycerol
  • Lipolysis
  • Triglycerides

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Physiology
  • Physiology (medical)


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