Jaime Ruiz-Tovar, MD, PhD, is a doctor of medicine at the Universidad Autónoma de Madrid and a specialist in general and digestive surgery at the Hospital del Henares in Madrid. He is Senior Lecturer in Surgery at the Universidad Alfonso X El Sabio (Madrid). He has been the supervisor of 15 doctoral theses, editor of 20 books, author of 90 book chapters and has published 219 manuscripts in high-impact international scientific journals. He has been awarded 15 national and international research grants; he received the Prize of the Royal National Academy of Medicine of Spain in 2014 and the Award of the Valencian Society of Surgery for the best scientific article published in 2015. He is currently leading several research projects focused on ERAS in bariatric surgery, different bowel length in gastric bypass, improvement of hepatic steatosis after bariatric surgery and implementation of fitness programmes for obese patients before and after bariatric surgery. Artur Marc-Hernandez, PhD, is Doctor of Sport Sciences at the Universidad Miguel Hernandez (Alicante, Spain). He is Senior Lecturer in Sport and Educational Sciences at the Universidad Europea de Madrid. He is the author of 10 book chapters and has published 8 manuscripts in high impact international scientific journals. He currently leads several research projects focusing on physical rehabilitation in ERAS programmes and the implementation of fitness programmes for obese patients before and after bariatric surgery.