The glucose-fatty acid cycle. Relationship between glucose utilization in muscle, fatty acid oxidation in muscle and lipolysis in adipose tissue.

This series of articles is concerned with how carbohydrate, lipid and amino acid metabolism in different tissues is integrated for the benefit of the whole animal. The tissues of the body oxidize a variety of organic compounds for production of biological energy in the form of ATP. These compounds include glucose, fatty acids, ketone bodies and some amino acids and for the purpose of these articles they can be grouped together under the term metabolic fuels. They are obtained either from the diet or from storage molecules such as glycogen, triacylglycerol and protein. It is crucial for the wellbeing of the animal that at least one of these metabolic fuels is always available in the bloodstream or the tissue despite large fluctuations in the rate of fuel utilization by the tissues or in the rate of fuel production from endogenous or exogenous sources. There is a vital need for the rate of production of a fuel to be regulated precisely in relation to its rate of utilization and for the rate of production and utilization of all fuels to be satisfactorily integrated. The present series of articles presents the author's own view of how this might be achieved.