Time-restricted Eating (TRE) and Protein in Older Adults

The Effects of Time-restricted Eating (TRE) With and Without Additional Protein on Body Composition, Muscle Function and Markers of Metabolic Health in Older Adults

The aim this study is to investigate the effects of time-restricted eating (TRE) on body composition, muscle function and markers of metabolic health of adults over 60 years old. This study will compare different variations of TRE - with and without an additional protein.

This study involves attending two study days at the University of Surrey for baseline and end-of-intervention measurement of body composition using a gold-standard dual energy x-ray absorptiometry (DEXA) scan; muscle function using hand grip strength and 30-second sit-to-stand tests; weight. A blood sample will be taken at each study visit to measure markers of lipid and glucose control, and insulin sensitivity.

Participants will be randomly allocated to one of four study groups:

• control group: maintain habitual dietary patterns
• TRE group: fast for 16 hours overnight, eat between 12-8pm
• TRE + Protein (AM): fast for 16 hours overnight, eat between 12-8pm; take a 30g plant-based protein supplement in the morning
• TRE + Protein (PM): fast for 16 hours overnight, eat between 12-8pm; take a 30g plant-based protein supplement in the afternoon Participants will be asked to follow the intervention according to their allocated group for 8 weeks.

Study Overview

• Status: Recruiting
• Conditions: Generally Healthy Adults Over 60 Years Old
• Intervention / Treatment: Other: TRE; Other: ProtAM TRE; Other: ProtPM TRE

• Study Type: Interventional
• Enrollment (Estimated): 80
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Yana Petkova; Phone Number: +44 7513 679 635; Email: yp00228@surrey.ac.uk
• Study Contact Backup: Name: Dr Collins; Email: a.collins@surrey.ac.uk

Study Locations

• United Kingdom
  • Guildford, United Kingdom, GU2 7XH
    • Recruiting
    • University of Surrey
    • Contact: Yana Petkova; Phone Number: +44 7513 679 635; Email: yp00228@surrey.ac.uk
    • Contact: Dr Collins; Email: a.collins@surrey.ac.uk
    • Principal Investigator: Dr Collins

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Gender: male and female
• Age range: 60 years or older
• Fasting for 12 or less hours on a daily basis
• BMI range: 23-30 kg/m2
• Weight stability: no more than 3kg weight gain or loss in the past 3 months
• Regular eating pattern, i.e. 3 meals a day
• Able to prepare the protein supplement

Exclusion Criteria:

• Any of the following present (in line with exclusion criteria used in previous TRE research in older adults):

  • known renal impairment
  • heart attack or stroke in the past three months
  • continuous use of supplemental oxygen to manage a chronic pulmonary condition or heart failure
  • rheumatoid arthritis
  • Parkinson's disease
  • active treatment for cancer in the past year
  • insulin dependent diabetes mellitus
• taking medications that preclude fasting for 16 h
• actively trying or planning to lose weight
• history of an eating disorder
• outside of stated age or BMI range
• fasting for longer than 12 hours on a daily basis
• unable to prepare the protein supplement
• extreme morning/evening chronotype
• sleep disorders
• regular meal skipping
• history of difficulty having a blood sample taken
• Recent exposure to high-dose radiation
• Vigorous exercise on more than 3 occasions a week

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Control
Experimental: TRE; Participants undertaking the TRE intervention	Other: TRE; Participants will be asked to follow a 16:8 TRE protocol, consuming all their daily within 8 hours, between 12 and 8pm, and fast for 16 hours overnight.; Outside of the eating window, participants will be allowed to consume energy-free drinks only, i.e. water, black tea/coffee, 0-calorie soft drinks.
Experimental: ProtAM TRE; Participants undertaking the ProtAM TRE intervention	Other: ProtAM TRE; Participants will be asked to follow a 16:8 TRE protocol, consuming all their daily within 8 hours, between 12 and 8pm, and fast for 16 hours overnight.; Outside of the eating window, participants will be allowed to consume energy-free drinks only, i.e. water, black tea/coffee, 0-calorie soft drinks.; In addition, they will be asked to consume a protein drink containing 30g protein in the morning, 2 hours before the 8-hour eating window opens at 12pm (i.e. at 10am).; Other Names: TRE + morning protein 'snack'
Experimental: ProtPM TRE; Participants undertaking the ProtPM TRE intervention	Other: ProtPM TRE; Participants will be asked to follow a 16:8 TRE protocol, consuming all their daily within 8 hours, between 12 and 8pm, and fast for 16 hours overnight.; Outside of the eating window, participants will be allowed to consume energy-free drinks only, i.e. water, black tea/coffee, 0-calorie soft drinks.; In addition, they will be asked to consume a protein drink containing 30g protein in the afternoon, either 2 hours after their first meal or 2 hours before their last meal of the day.; Other Names: TRE + afternoon protein 'snack'

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline in body composition at 2 months using whole-body dual-energy x-ray absorptiometry (DEXA)	Measured using whole-body dual-energy x-ray absorptiometry (DEXA) In addition to the above, body composition will also be assessed using Tanita Bioelectrical impedance analysis (BIA). Fat free and fat mass will be reported in kg.	For 8 weeks of the assigned study intervention
Change from baseline in muscle function at 2 months	Measured using grip strength	At the start and end of 8 weeks of the assigned study intervention
Change from baseline in muscle function at 2 months	Measured using 30-second sit-to-stand test.	At the start and end of 8 weeks of the assigned study intervention

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in fasting glucose control indicators	HbA1c	At the start and end of 8 weeks of the assigned study intervention
Change from baseline in insulin sensitivity at 2 months	HOMA-IR	At the start and end of 8 weeks of the assigned study intervention
Change from baseline in lipid metabolism at 2 months	fasting total, LDL- and HDL cholesterol and triglyerides	At the start and end of 8 weeks of the assigned study intervention
Change from baseline in diet composition at 2 months	Macro- and micronutrient analysis using the nutrition analysis platform Nutritics of 3-day food diaries administered at the start, mid-point and end of the assigned study intervention.	At the start, mid-point (week 4) and end of 8 weeks of the assigned study intervention
Feasibility of the assigned TRE intervention	semi-structured interviews	at the end of the 8 week intervention

Collaborators and Investigators

• Sponsor: University of Surrey

Study record dates

Study Major Dates

• Study Start (Estimated): December 1, 2025
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: November 26, 2025
• First Submitted That Met QC Criteria: December 17, 2025
• First Posted (Estimated): January 2, 2026

Study Record Updates

• Last Update Posted (Estimated): January 2, 2026
• Last Update Submitted That Met QC Criteria: December 17, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Glycoside Hydrolases; Hydrolases; Enzymes; Enzymes and Coenzymes; Disaccharidases; Trehalase
• Other Study ID Numbers: 361019

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Not required or applicable for this study protocol

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No