Table 1

Inclusion and exclusion criteria of the observational cohort study and feasibility randomised controlled trial

Inclusion criteria	Exclusion criteria
Observational cohort study
Aged 65 years or older	Unable to provide informed consent
Admitted to geriatric rehabilitation	Patients in isolation/quarantine
Written informed consent	Any condition that prevents completion of the study
	Palliative care
	Not possible to communicate in Dutch
Feasibility randomised controlled trial
Aged 65 years or older	Unable to provide informed consent and no proxy to consent
Admitted to geriatric rehabilitation	Rehabilitation after stroke or cancer
Diagnosed with sarcopenia (EWGSOP2 definition)	Patients in isolation/quarantine
Written informed consent	Palliative care or other adverse prognosis precluding post-intervention follow-up
	Ongoing cancer treatment or radiotherapy/ chemotherapy in the last 6 months
	Any GI disease that interferes with bowel function and nutritional intake
	Other relevant medical history or medication that could prevent participation in the
	intervention or affect the study outcome
	Patients with tube feeding at admission to geriatric rehabilitation.
	Renal impairment (estimated glomerular filtration rate <30 mL/min/1.73 m²)
	Body mass index >40 kg/m²
	Known soy allergy, known cow’s milk protein allergy or galactosaemia, known severe
	Lactose intolerance; patients requiring a fibre-free diet
	Current alcohol or drug abuse in opinion of the investigator
	Not possible to communicate in Dutch
	Uncertainty about the willingness/ability of the subject to comply with the protocol
	Participation in other intervention studies
	For BIA measurements only: electronic implant and/or pacemaker*

*Our aim is to assess muscle mass in minimum 60 participants. Therefore, a maximum of 20 patients with an electronic implant/pacemaker will be included in the study.
BIA, bioelectrical impedance analysis; EWGSOP, European Working Group on Sarcopenia in Older People; GI, gastrointestinal.