After his PhD, he was awarded a post-doctoral fellowship by the Ingestive Behavior Research Center at Purdue University (Indiana, USA), where he worked with Distinguished Professor Richard Mattes for 3 years. Dr. Tan's research includes: 1) post-ingestive physiological responses (e.g. insulin release, energy expenditure and substrate oxidation), 2) human feeding behaviours (e.g. objective and subjective assessment of appetite, sensory influences on food selection, and factors that determine food intake), 3) weight loss interventions with special interest in visceral fat mass changes, and 4) accelerometry in predicting physical activity.