Portion size is an essential component of dietary assessment. However, methods of quantifying portion size can differ between studies. This episode, we speak with Dr. Birdem Amoutzopoulos, Dietary and Nutrient Data Manager at The Medical Research Center Epidemiology, University of Cambridge. She is the lead author for the article "Portion size estimation in dietary assessment: a systematic review of existing tools, their strengths and limitations" featured in the November 2020 print issue of Nutrition Reviews.