Investigating the effect of partial meal replacements on weight loss for people awaiting knee or hip arthroplasty

Participants who are awaiting a hip or knee replacement at the Fairfield Orthopaedic Hip and Knee Service (FOHKS) will be invited to attend a group education session of 5-10 people in each group either in person at the South Western Sydney Metabolic Rehabilitation and Bariatric Program (MRBP) or via a telehealth connection if pandemic related health restrictions are in place. There will be three education sessions, for 1 hour each, will be based on partial meal replacement (two meal) advice and lifestyle advice from a dietitian, and an app and educational material developed by collaborators from the Counterweight UK team. This dietitian will be supported by a dietitian from Counterweight UK, as well as an obesity specialist endocrinologist and metabolic Clinical Nurse Consultant from the South Western Sydney Metabolic Rehabilitation and Bariatric Program where required. The complete PMR plan will provide 1200 calories/day, and participants will be provided with meal replacement shakes to cover 2 meals per day for 12 weeks (168 in total) free of cost over the course of the study. The shakes provided are manufactured by Counterweight UK, and are commercially available. Counterweight UK have also developed an app as well as education materials for people on partial meal replacements which are part of their commercially available meal replacement programs. The intervention support includes access to this structured App with tracking, nutrition education content, and behavioural strategies to support weight loss; group education sessions at 0, 6 and 12 weeks, and readily available educational videos, (face to face with the option of video conferencing if pandemic related health restrictions remain at the time of the study). There will also be 3 x 1:1 15-30 minute telephone/telehealth support with a dietitian trained in motivational interviewing at weeks 2, 4 and 9, and the dietitian will discuss adherence to the intervention during the group sessions as well as the telephone/telehealth sessions. The recommendation will be for the app to be accessed at least once per week to log measurements (e.g., weight), read educational content and review goals/activities. The dietician will further review educational content read (in %) and measurements logged to assess the participant’s adherence to app usage. At each education session and telephone consultation , participants will receive general advice about the meal replacements and portion controlled meals, avoidance of snacking, fluid intake and will also have an opportunity to discuss any specific issues and their progress including queries regarding the app. At the 12-week visit, the dietitian will provide advice on weight loss maintenance with the option of participants continuing the recommended meal replacements (as part of portion control) at their own expense if they choose (using commercially available shakes). To assess whether weight loss is maintained without ongoing support, participants will be encouraged to aim for weight stabilisation prior to surgery and for all participants to be on a minimum 1600 calories/day by time of surgery, with a repeat assessment conducted at least 4 weeks after the 12-week visit. Potential participants will be identified by Fairfield Orthopaedic Hip and Knee Service clinicians based on inclusion and eligibility criteria. The participants will be provided with the participant information sheet. Those that show interest will be asked permission from a member of the research team to contact them by telephone at least 24 hours later. Participants who meet study criteria will be invited to participate. Preference will be given to patients with a higher BMI (>35kg/m2)