Department of Human Evolutionary Biology, Harvard University
Friday 2:15-2:30, Galleria South
Extensive dietary processing is a unique and universal human trait with potentially significant consequences for past and present energy metabolism. However the energetic effects of food processing can be difficult to study in humans due to the high degree of experimental control required and concerns related to the consumption of unprocessed foods. We have thus employed animal models in the pursuit of such questions. Our model-based research has previously demonstrated that the adoption of food processing technologies would have been energetically significant events, with non-thermal processing improving starch-rich plant foods, and cooking improving both meat and starch-rich plant foods regardless of prior processing by non-thermal methods. To better understand the mechanisms responsible for the increased energetic potential of processed diets, we have again turned to animal models to test the hypothesis that cooking and non-thermal processing reduce diet-induced thermogenesis, the metabolic cost of digestion. In a collaborative study of pythons fed meat diets, cooking and non-thermal processing each lowered diet-induced thermogenesis by 12%, and their combined effects were nearly additive, with cooked/ground diets generating 23% less thermogenesis than raw/whole diets. A recent replication of this study among rats fed meat and tubers served raw/whole, raw/pounded, cooked/whole and cooked/pounded confirms that food processing reduces the thermogenic response, controlling for meal size and the metabolic contributions of activity. Implications for modern human nutrition and the evolution of human energy budgets are discussed.
This work was supported by the National Science Foundation (DDIG BCS-0962038 and GRFP), The Leakey Foundation, and the Department of Human Evolutionary Biology at Harvard University.