This review discusses the metabolic changes that occur during fasting, especially in relation to surgical stress. Currently available evidence on the relevance of different aspects of perioperative nutritional support are presented. Attenuation of surgical stress and insulin treatment in insulin-resistant patients after surgery and trauma have been shown to markedly affect stress metabolism as well as patient morbidity and mortality. Avoiding preoperative fasting has been shown to be related to a substantial reduction in postoperative stress and insulin resistance. Implementation of a standardized programme with a multimodal approach using evidence-based perioperative routines has been shown to further reduce surgical stress and to markedly enhance functional recovery also after major surgical procedures.