RecruitingACTRN12626000604303

Plant-based and Animal-based Protein Diets on Muscle Growth and Functional Health in Overweight Elderly - Feasibility study (Phase 2)

PLANIMO - PLant-based and ANImal-based Protein-source Diets on Muscle Synthesis and Functional Health in Overweight Elderly - Feasibility study (Phase 2)

Sponsor

Deakin University

Enrollment

60 participants

Start Date

May 5, 2026

Study Type

Interventional

Conditions

Sarcopenia

Summary

AIM: The overall aim of the feasibility study is to investigate the effect of a plant-protein and animal-based diet on healthy ageing. OBJECTIVES: 1) The primary objective, in the context of preserving musculoskeletal health as a key component of healthy ageing, is to assess the effect of plant-based and animal-based protein-source diets on muscle fractional synthesis rates in overweight elderly over time. 2) The secondary objectives, aligned with broader determinants of healthy ageing, are to evaluate the difference in plant-based and animal-base protein-source diets on metabolic function (inflammatory markers, glucose variability and lipid profile), cardiovascular outcomes (vascular function and stiffness), feasibility, acceptability and compliance, dietary composition (macronutrients/micronutrients/amino acids/dietary protein quality), and greenhouse gas emissions (life cycle analysis). 3) The exploratory objectives are to evaluate differences in plant-based and animal-based protein-source diets on chemical and activity-based biological ageing markers (proteomic, metabolomic, lipidomic, and physical activity). This study addresses the knowledge gap on the real-life effects of a plant- and animal-protein whole-food diet on muscle protein synthesis and functional health outcomes in elderly and may lay the foundation for more extensive research. The study can guide sample size calculations, methodology, and feasibility of future intervention studies in the same field. The study can help find barriers and refine strategies to reach the target group. Findings may further help guide recommendations for protein intake in the elderly population, and help understanding of the biological mechanisms of the global transition to a more plant-based protein-source diet in the elderly population. Investigation of the exploratory outcomes can help generate hypotheses to inform future research, by providing insight into how molecular pathways affect healthy ageing, thereby supporting the primary aim

Eligibility

Sex: Both males and femalesMin Age: 65 Yearss

Inclusion Criteria1

The study will include 60 participants, and older adults with an overweight BMI, aged 65 years or more may be eligible to participate.

Exclusion Criteria1

Participants with one or more of the following will be excluded from being able to participant: diagnosed myopathy, IBS or IBD, diabetes, medicated with immunosuppressant medication, blood thinning medication, blood pressure medication, cholesterol lowering medication, allergy to anaesthesia or living in a care home. Individuals will also be excluded from the study if they do structured resistance exercise more than once a week.

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Interventions

INTERVENTION GROUPS: The intervention is a 14-day dietary intervention, with a total of 4 visits. Visit 1 is a 1-hour phone call, including an explanation of all measures of the study. Visit 2

INTERVENTION GROUPS: The intervention is a 14-day dietary intervention, with a total of 4 visits. Visit 1 is a 1-hour phone call, including an explanation of all measures of the study. Visit 2 is a physical visit to Deakin University. At this point, all the participants have been allocated to their intervention groups. At visit 2, all participants will receive dietary counselling as well as a 14-day dietary plan by a dietitian on how to follow an isocaloric diet providing 1-1.2g of protein per kg of body weight. The 14-day dietary plan includes a shopping list for all foods needed for the intervention, as well as ingredients and recipes for all meals of the entire 14 days. Participants do not receive any foods from the study. All participants will receive two phone calls (on days 5 and 10 of the intervention) during the intervention from a dietitian in the team to ensure adherence to the diet. If any issues or dislikes occur with the diet, the team dietitian will adjust the diet. These adjustments include but are not limited to swapping out foods for foods that are better tolerated or liked, as well as potentially increasing or decreasing food volume, or spacing meals differently. The study will involve three intervention groups, including a control group (Intervention Group C). 1. Intervention A: Will consume a diet with 100% plant-based protein sources. 2. Intervention B: Will consume a diet with 70% plant-based and 30% animal-based protein sources. 3. Intervention C (Control Group): Will consume a diet with 30% plant-based and 70% animal-based protein sources (closely resembling the current dietary protein distribution in Australia). All the intervention groups will be supervised by dieticians who will tailor the diet to comply with the recommended daily nutrient intake. In addition, the diet will be aligned with the sensory needs and close to dietary habits, allowing a smooth behavioural transition. Examples of protein sources being used as plant protein are: legumes, nuts & seeds, vegetables, cereals and bread etc. Examples of protein sources being used as animal protein are: eggs, meat, poultry, fish etc.