Objective: Enhanced Recovery After Surgery (ERAS) is a multidisciplinary approach that aims to optimize perioperative management, promote postoperative recovery, reduce postoperative complications, and improve long-term survival. The current study aimed to evaluate and compare the postoperative physical activity after gastrectomy between patients who underwent upper gastrointestinal surgery according to ERAS and those who underwent surgery based on the conventional care (CC) protocol. Materials and Methods: This prospective and retrospective review enrolled 60 patients (n = 31, ERAS group; n = 29, CC protocol group) diagnosed with adenocarcinoma of the stomach and esophagogastric junction who underwent curative surgical resection. Physical outcomes, including body weight, body mass index, body fat percentage, basal metabolic rate, muscle mass, gait speed, and handgrip strength at the preoperative and immediate postoperative periods and at 1, 3, and 6 months postoperatively, were comparedbetween the ERAS and CC protocol groups. Results: One month after surgery, the ERAS group had a lower percentage of body weight loss than the CC protocol group. There was no significant difference in terms of muscle mass loss between the two groups. The hand grip strength of the ERAS group increased after surgery. Further, at 1 month postoperatively, the gait speed of patients who underwent total gastrectomy in the ERAS group was significantly higher than that of patients in the CC protocol group. Conclusion: ERAS for gastrectomy was associated with a lower percentage of weight loss and a trend toward physical activity enhancement in the early postoperative period.