Objective: To evaluate the effect of feeding with a whey protein plus carbohydrate drink on metabolic parameters, general state of the patient and recovery time after knee and hip arthroplasty. Methods: The results of the perioperative period of 60 patients with osteoarthritis (OA) of the hip and knee were evaluated between March and July 2021. All patients underwent hip or knee arthroplasty under spinal anaesthesia. In addition, patients of the study group received the ProvideXtra® Drink 2 hours before surgery. Otherwise, the management of patients in the perioperative period was the standard. Mobilisation and verticalisation of patients were carried out after achieving physical fitness, resolution of the spinal block and haemodynamic stability on the day of surgery or the next day. Results: In all patients after 4 hours, increased glucose levels were recorded in both groups, statistically significant in the control group – 7.15±0.94 versus 7.88±1.18 mmol/l (p=0.02). The decrease in haemoglobin level had no difference in the study groups and before discharge was 100±16 g/l versus 101±18 g/l (p=0.86). The difference in total protein level before discharge was in favour of the study group, 63.1±6.1 versus 59.2±5.9 g/l (p=0.17). Verticalisation timing in the study group was as follows: 10 patients were verticalised on the day of surgery, and the remaining 20 patients – were on the next day. In the control group – 8 patients were verticalised on the day of surgery and 22 – on the next day. In the control group, 2 cases of postoperative nausea requiring correction were observed. Conclusion: The modern surgical approaches include the maximal preservation of natural feeding, based on the Enhanced Recovery after Surgery (ERAS®) concept. However, guidelines for choosing a particular diet on the day of surgery remain to be finally established. Using ready-made carbohydrate-protein mixtures is a convenient solution that delivers the required amount of energy and protein. Therefore, the effect of the mixture on protein metabolism in the postoperative period remains to be elucidated through further studies. Keywords: Accelerated rehabilitation, nutrient mixture, hip arthroplasty, knee arthroplasty.