Stable isotope approaches for study of energy substrate metabolism.

Stable isotopes can be used to assess various aspects of energy metabolism. This paper reviews recent experiments in which we have used stable isotopes, either alone or in conjunction with radiolabeled isotopes, to investigate carbohydrate, fat, and protein metabolism in both animals and human subjects. The approaches described allow investigation of the interrelationships of substrate kinetics and oxidation in vivo in ways not possible with radiolabeled isotopes alone.