John Roger Speakman is a British biologist working at the University of Aberdeen, Institute of Biological and Environmental Sciences, for which he was Director from 2007 to 2011. He leads the University's Energetics Research Group, which is one of the world's leading groups using doubly labeled water (DLW) to investigate energy expenditure and balance in animals. Between 2011-2020, he was  a '1000 talents' Professor at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, in Beijing, China, where he ran the molecular energetics group. In 2020 he moved to the Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences in Shenzhen, China where he is currently co-director of the Center for Energy Metabolism and Reproduction and Head of the Shenzhen Key laboratory of Metabolic Health.

He runs two research groups: one in Beijing China and one in Aberdeen, Scotland. His work focusses on energy balance - the factors that govern variation in food intake and energy expenditure, and the consequences for fat storage (obesity) and other physiological parameters such as oxidative stress and ageing. This includes studies in free-living and captive animals, and humans. Their work stretches from the gene to the individual and increasingly includes a systems biology perspective.