Harriët Jager-Wittenaar, PhD, RD, is Professor of Malnutrition and Healthy Ageing at the Hanze University of Applied Sciences, and senior researcher at the University Medical Center Groningen The Netherlands. In her research program, dr. Jager-Wittenaar focuses on prevention and treatment of malnutrition and sarcopenia, nutritional assessment (e.g., body composition assessment), implementation of nutritional risk screening and nutritional assessment, and the relationship between malnutrition and frailty. From September 2017, dr. Jager-Wittenaar leads the European Specialist Dietetic Network (ESDN) for Older Adults, an expert committee within the European Federation of Associations of Dietitians (EFAD). Since June 2018, dr. Jager-Wittenaar is Movement and Rehabilitation Fellow at the Vrije Universiteit Brussel. She is active in ESPEN, as co-developer and teacher of the LLL course Nutritional support in cancer and member of the GLIM Validation and Testing Study Group.