Investigating the effect of a weight loss intervention on kidney disease progression: a randomised controlled feasibility study

*Low energy diet stage 12 weeks >>> Diet Intervention group participants will follow a three-month low energy diet (LED) (~3400 to 3700 kJ, ~80g protein per day), using 3 to 4 commercial meal-replacements (Optifast, Nestle each product ~840 to 950 kJ) + 0-1 low energy food items + 2 cups of low carbohydrate vegetables every day + encouraged to consume x 1 tsp of oil and 2 litres of energy free beverages per day (preferably water). All meal replacements for the duration of the study will be provided to participants. Low energy foods are defined as individually portioned snacks with an energy content of 800-1000kJ, such as 1 packet breakfast biscuits (Belvita, 50g), 1 breakfast bakes bar (uncle Toby's, 65g), 1 packet of nuts, or nuts and seeds (Luck,y 30g), 1 snack packet of cheese and crackers (5 cheese slices, 5 crackers, 50g), 1 small tin salt reduced baked beans (Heinz, 220g), 1 red kidney bean salad (Edgell, 200g), 1 tuna and crackers snack pack (Woolworths, 112g), 1 tuna & pasta/quinoa/beans (Woolworths, tuna & pasta marinara sauce 170g, tuna & pasta Sicilian style 170g, tuna & quinoa Asian style 185g, tuna & beans Mexican style 185g, 1 tuna ready to eat (Sirena, Sicilian style pasta with tuna 170g, Italian style salad with tuna 170g, kale & quinoa salad with tuna 170g), or 1 tuna meal (John West, tuna & beans, capsicum, sweet corn, red kidney beans & chilli 185g, tuna lunch kit thousand island dressing 108g, protein + iron tuna with roasted capsicum & three bean mix 170g, protein + magnesium tuna with brown rice, chargrilled corn, black beans, lime & chilli 170g) The initial appointment (30 min) will include written and verbal information for the diet and for fluid intake and outline the group support program. Written information has been developed specifically for this study and includes written and pictorial information on the commercial meal-replacements and low energy foods. To support participants in this stage, they will have fortnightly contact with a specialist kidney dietitian (minimum 5 years’ experience) in a structured education support group (6 x 45 minute sessions) using telehealth, and an optional virtual patient support group (using a group chat app) to share experiences and encouragement in this stage. THe maximum group size will be 8 participants. Structured education (a combination of teaching, practical activities and discussion in the group and self monitoring between sessions) will include awareness of hunger and satiety and eating habits, reasons for eating, and problem solving using a motivational interviewing approach. Additional telephone/text message/telehealth support will be available for participants as clinically appropriate during the low energy diet stage. Time spent in additional support will be based on clinical need as assessed by the research dietitian. Participants in the intervention group will have a “kidney” blood test 2-4 weeks after commencing the low energy diet, to monitor serum electrolytes, creatinine (and estimated eGFR) and lipids. The results will be screened by the study site Dietitian or research nurse, and any results out of usual range for the participant highlighted, and all results sent to the nominated study nephrologist for review. The nephrologist will review, sign, and date the results and indicate ‘NCS’ if not clinically significant or ‘CS’ next to a particular result if deemed clinically significant. All clinically significant results will be sent to the participant’s usual kidney specialist for review and the intended action documented and communicated to the participant and participant’s General Practitioner (GP) by a member of the study team. The frequency of any ongoing monitoring of blood tests or symptoms will be determined by the usual kidney specialist and carried out by the study team. >>>Physical activity Participants' will be instructed to continue physical activity and exercise habits during this LED phase. Adherence will be monitored using attendance checklists and meal replacement + snack diaries. *Food reintroduction and lifestyle adaptation stage 12 weeks >>>Eating and Physical Activity Immediately following the LED stage, participants will initially attend fortnightly and then monthly 45 minute facilitated telehealth group sessions, for a further 3 months (a total of 4 sessions across 3 months, facilitated by an experienced kidney dietitian with > 5 years experience and an accredited Clinical Exercise Physiologist), to support the introduction of a physical activity program, develop healthy eating, self-efficacy, strategies to change habits, new normal routines for eating and physical activity and for peer support. The virtual patient support group will continue during this stage. Food re-introduction will occur in a planned stepwise manner and pragmatically in line with participant readiness, with goal intakes increasing to 6000 kJ/day, through to standard energy requirements minus 2000 kJ/day, for ongoing weight loss, capped at 10 000 kJ/day. If weight regain of >2kg occurs, participants will be encouraged to use meal replacements for 1-2 meals per day for 1-2 weeks, and will receive additional support and review of barriers/eating/activity for weight loss maintenance. Individualised, graded physical activity plans will be developed with the study Accredited Exercise Physiologist (minimum 2 years’ experience) - based on self-identified activity goals, and activity tracked and monitored virtually with a phone/tablet/computer app. The individual program is based on exercise recommendations and guidelines from the American College of Sports Medicine. The program will include a combination of upper and lower body movements (e.g. TheraBand chest press and row, bicep curl, sit to stand, hip bridge and leg curl exercises), cardiovascular exercise (e.g walking, jogging and cycling), and mobility exercises (e.g.stretching, wall angels, roll downs and knee rocks), with an overall aim to increase strength, maintain or improve muscle mass, and improve cardiovascular fitness. The intensity and volume of exercise is based on the participants medical history, disease state, goals and identified barriers, aiming to progressively increase to at least 150 minutes of physical activity per week. The physical activity program is entered into the PhysiTrak software for participants to complete at home in their own time. Participants enter their exercise into Physitrak and this is monitored by the exercise experts in the study team on a weekly basis. In alignment with previous research the participants will be supported through fortnightly to monthly sessions using telehealth (4 x 45-minute sessions). Additional support by telephone, text message and telehealth is available to participants if requested, or if planned exercise is not recorded as completed. All participants attend usual kidney clinic visits with treatment aiming for optimal blood pressure, lipid and glycaemic control with standard medical therapies treating to national guidelines. There will be no change to frequency of usual nephrologist care or general practitioner shared care monitoring. There will be no change to referral criteria for dietitian consultations. A sub-sample of participants will be invited to complete semi-structures interviews to provide information about participant experience during the study. All participants will be offered the opportunity to participate until the required sample of 6-8 participants from the intervention group is reached.