Compositions and methods for forming hydrocarbon products from triglycerides are described. In one aspect, the methods involve the thermal decomposition of fatty acids, which can be derived from the hydrolysis of triglycerides. The thermal decomposition products can be combined with low molecular weight olefins, such as Fischer-Tropsch synthesis products, and subjected to molecular averaging reactions. Alternatively, the products can be subjected to hydrocracking reactions, isomerization reactions, and the like. The products can be isolated in the gasoline, jet and/or diesel fuel ranges. Thus, vegetable oils and/or animal fats can be converted using water, catalysts, and heat, into conventional products in the gasoline, jet and/or diesel fuel ranges. These products are virtually indistinguishable from those derived from their petroleum-based analogs, except that they can have virtually no aromatic, sulfur or nitrogen content, they are derived, in whole or in part, from renewable resources, and can also be derived from domestically available coal and/or natural gas.