Having discussed bioenergetics from the impact of evolution on metabolism through to the regulation of energetics in response to multiple environmental factors, Suarez concludes that this collection of reviews will ‘demonstrate that the study of energy metabolism in animals continues to be relevant, exciting and fundamentally important’. Pointing out that energy metabolism responds to climate change and has to adapt in many organisms if they are to survive, Suarez adds that bioenergetics is also relevant to human health and welfare, affecting every aspect of our ecosystem at this time of rapid environmental change.