Effect of a High-Protein, High-Fiber Pre-Fast Meal on Satiety and Glycemic Profiles During Fasting (FAST-SAT)

Effect of a High-Protein, High-Fiber Pre-Fast Meal on Satiety and Glycemic Profiles During Fasting: A Randomized Crossover Study

This randomized crossover study investigates the effect of consuming a high-protein, high-fiber pre-fast meal on subjective satiety and glycemic responses during fasting hours in healthy adults. Participants will complete two dietary conditions in a randomized order: a standardized high-protein, high-fiber pre-fast meal and a low-protein, low-fiber pre-fast meal guided by dietary instructions. Each condition will be followed for two consecutive days and separated by a three-day washout period. Outcomes include subjective appetite sensations during fasting hours, glycemic profiles assessed using continuous glucose monitoring (CGM), and exploratory analyses examining the association between glucose dynamics and appetite sensations.

Study Overview

• Status: Recruiting
• Conditions: Dietary Intervention; Glycemic Response; Satiety; Postprandial Glucose; Fasting, Time Restricted
• Intervention / Treatment: Other: High-Protein, High-Fiber Meal; Other: Low-Protein, Low-Fiber Meal

Detailed Description

This study is a randomized crossover interventional trial conducted in healthy adults to evaluate the effect of a high-protein, high-fiber pre-fast meal on subjective satiety and glycemic responses during fasting hours.

Each participant will complete two study conditions in a randomized sequence: a high-protein, high-fiber pre-fast meal condition and a low-protein, low-fiber pre-fast meal condition. Each condition will be followed for two consecutive days and separated by a three-day washout period to minimize potential carryover effects.

During the high-protein, high-fiber condition, participants will consume a standardized pre-fast meal consisting of oats (40 g), Greek yogurt (160 g), peanut butter (16 g), dried cranberries (10 g), and almonds (6 g). Meals will be provided in pre-measured portions by the research team.

During the low-protein, low-fiber condition, participants will receive standardized written dietary instructions, including a list of foods to avoid, to guide consumption of a low-protein, low-fiber pre-fast meal. No calorie restriction will be applied in either study condition.

Subjective appetite sensations, including hunger, fullness, desire to eat, and prospective food consumption, will be assessed using visual analogue-type scales at predefined time points across the fasting day. Glycemic profiles will be continuously assessed using continuous glucose monitoring (CGM).

Exploratory analyses will examine temporal associations between CGM-derived glucose levels and glucose trends and subjective appetite sensations across the study day.

• Study Type: Interventional
• Enrollment (Estimated): 38
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Wafa Alotaibi; Phone Number: +966500358622; Email: Walotaibi@kfu.edu.sa

Study Locations

• Saudi Arabia
  • Eastern Province
    • Al-Ahsa, Eastern Province, Saudi Arabia, 31982
      • Recruiting
      • King Faisal University
      • Contact: Wafa Alotaibi, PhD; Phone Number: +966135897656; Email: Walotaibi@kfu.edu.sa

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Adults aged 18 years and older
• Willingness to comply with study procedures, including fasting and continuous glucose monitoring
• Ability to provide informed consent

Exclusion Criteria:

• Diagnosed diabetes mellitus or known metabolic disease
• History of cardiovascular, gastrointestinal, or endocrine disorders that may affect study outcomes
• Use of medications known to affect glucose metabolism or appetite
• Pregnancy or lactation
• Known allergy or intolerance to any study meal components (oats, dairy, peanuts, nuts, cranberries)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High-Protein, High-Fiber Pre-Fast Meal; Participants consume a standardized high-protein, high-fiber pre-fast meal for two consecutive days.	Other: High-Protein, High-Fiber Meal; Participants consume a standardized high-protein, high-fiber pre-fast meal consisting of oats (40 g), Greek yogurt (160 g), peanut butter (16 g), dried cranberries (10 g), and almonds (6 g) for two consecutive days.
Active Comparator: Low-Protein, Low-Fiber Pre-Fast Meal; Participants follow standardized written dietary instructions to consume a low-protein, low-fiber pre-fast meal for two consecutive days.	Other: Low-Protein, Low-Fiber Meal; Participants follow standardized written dietary instructions, including a list of foods to avoid, to consume a low-protein, low-fiber pre-fast meal for two consecutive days. No calorie restriction is applied.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Daytime Satiety During Fasting Hours	Subjective appetite sensations including hunger, fullness, desire to eat, and prospective food consumption assessed using a visual analogue-type scale with numeric anchors ranging from 0 to 10.	Assessed at baseline prior to the pre-fast meal, 30 and 60 minutes post-meal, mid-afternoon (approximately 4:00 PM), and 30 minutes prior to breaking the fast during each intervention condition.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycemic Profiles During Fasting (CGM)	Interstitial glucose levels assessed using continuous glucose monitoring (CGM) to evaluate glucose patterns and variability during fasting hours.	Assessed on Day 1 and Day 2 of each intervention period during the fasting window from completion of the pre-fast meal until breaking the fast.
Post-Meal CGM Glucose Response	Continuous glucose monitoring-derived glucose response in the 0-120 minutes following consumption of the pre-fast meal, including peak glucose and incremental area under the curve (iAUC).	0-120 minutes after the pre-fast meal during each intervention condition.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Association Between Glucose and Appetite (Exploratory)	CGM Glucose Concentration and Subjective Appetite Ratings at Predefined Time Points	Assessed on Day 1 and Day 2 of each intervention period at the predefined appetite assessment time points: baseline prior to the pre-fast meal, 30 minutes post-meal, 60 minutes post-meal, 4:00 PM, and 30 minutes prior to breaking the fast.

Collaborators and Investigators

• Sponsor: King Faisal University
• Collaborators: Saudi Food and Drug Authority

Study record dates

Study Major Dates

• Study Start (Actual): February 23, 2026
• Primary Completion (Estimated): March 23, 2026
• Study Completion (Estimated): March 23, 2026

Study Registration Dates

• First Submitted: February 22, 2026
• First Submitted That Met QC Criteria: February 26, 2026
• First Posted (Actual): March 3, 2026

Study Record Updates

• Last Update Posted (Actual): March 12, 2026
• Last Update Submitted That Met QC Criteria: March 10, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Behavior; Feeding Behavior; Fasting; Intermittent Fasting; Therapeutics; Diet, Food, and Nutrition; Physiological Phenomena; Nutritional Physiological Phenomena; Diet Therapy; Nutrition Therapy; Diet; Diet, Protein-Restricted
• Other Study ID Numbers: KFU-2026-ETHICS3958

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data (IPD) collected in this study will not be made publicly available. Data will be used for research purposes by the study investigators only

Drug and device information, study documents

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