Advanced Protein-based Program for Effective Treatment of Appetite Regulation and Obesity (APPETITE)

A Single-blind Randomised Study to Test the Effects of Protein-enriched Breakfast Meals With Varying Protein Sources Compared to a Standard Meal on the Regulation of Appetite and Satiety in Healthy Human Volunteers

INTRODUCTION: Obesity is a global epidemic, with over 2.5 billion adults being classified as overweight and 890 million of these classified as obese. Overweight and obesity are the 5th cause of mortality globally, with an estimated 2.8 million related deaths among adults. The rising prevalence of obesity in adults is leading to a rise in the prevalence of type 2 diabetes, with an estimated 462 million individuals affected globally. At present, the most effective non-surgical obesity treatments offered by the National Health Service (NHS) are the subcutaneously administered GLP-1 receptor agonists. However, they may present potentially serious side effects following short-term use, and there are still uncertainties around long-term use side effects. Therefore, a dietary approach to weight loss or maintenance seems preferable.

Increasing protein intake is a commonly applied nutritional approach to appetite regulation. The increase in protein intake is often achieved by supplementation, using proteins isolated from dairy, such as whey and casein. However, with more individuals following plant-based diets over recent years, the interest in plant-based protein supplements has increased. While dairy-based proteins are well-characterised, the appetite regulatory characteristics of plant-based proteins have not yet been fully elucidated.

The main aim of this study is to investigate the effects of protein-enriched food items on appetite regulation compared to a standard carbohydrate-rich meal. Furthermore, this study will investigate whether there are any differences in appetite-related hormonal responses to a plant protein-containing meal replacement shake (containing rice and pea protein) or a potato protein-enriched standard carbohydrate-based meal compared to a whey protein-enriched standard carbohydrate-based meal.

Study Overview

• Status: Completed
• Conditions: Appetite and General Nutritional Disorders
• Intervention / Treatment: Other: Oat porridge; Dietary supplement: Whey protein isolate; Dietary supplement: Potato protein isolate; Dietary supplement: Meal replacement shake

Detailed Description

Intervention study with four treatment groups in a randomised, single-blind, quadruple crossover design.

Healthy male participants (between the ages of 18 to 50 years) will receive four different isocaloric intervention meals with the same mass, on separate visit days, following a minimum of 8 hours overnight fast. The four meals will contain oat porridge prepared with coconut milk as a control, oat porridge prepared with coconut milk with added whey or potato protein isolates, and a complete meal replacement shake containing plant-based pea and rice proteins. The intervention meals will be followed by a standardised pasta-based ready meal after the 3-hour observation period. All participants will observe at least a two-day washout period between the differing treatments.

Biological samples (blood) will be collected at various times during the visit. Blood samples will be collected at baseline 0 min prior (T0), then at 30 min (T30), 60 min (T60), 120 min (T120) and 180 min (T180) after the intervention meal consumption.

In addition, pertinent questionnaires, Visual Analogue Scale [VAS] for assessing satiety and VAS for assessing intervention meals' perception and palatability will be collected. VAS for the assessment of satiety will be collected at T0, T30, T60, T120 and T180 and VAS assessing the perception and palatability of the intervention meals will be collected immediately following meal consumption.

• Study Type: Interventional
• Enrollment (Actual): 12
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United Kingdom
  • London, United Kingdom, W1W 6UW
    • Centre for Nutraceuticals School of Life Sciences, University of Westminster

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Males (18-50 years of age)
• Lean and Overweight subjects (BMI 18.5 - 30 kg/m2)
• Sedentary and physically active subjects
• Healthy subjects

Exclusion Criteria:

• Female
• <18, >50 years
• Dieting
• Consumption of >14 units of alcohol/week
• Allergies to test foods/drinks
• Illnesses or on medication (with a possible effect on taste and/or appetite)
• Devices such as pacemakers
• Smokers
• Gastrointestinal disorders
• Eating disorders

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Sham Comparator: Oat porridge; Control Meal (9.5 g total protein)	Other: Oat porridge; Oat flakes, 81g (equivalent to 9 g of protein), were presented to participants in the form of porridge, prepared with 500 mL coconut milk (equivalent to 0.5 g of protein) and 10 g of zero calorie sugar free syrup. The total energy content was equivalent to 400 Kcal. Participants were instructed to consume the entire meal presented to them in 15 minutes on an empty stomach when attending the study.
Active Comparator: Oat porridge with whey protein; (total protein 40.5 g; of which whey protein isolate contributed 34.2 g of protein)	Dietary supplement: Whey protein isolate; Whey protein isolate, 38g (equivalent to 34.2 g of protein), was presented to participants in the form of a porridge. Other ingredients in the whey protein enriched porridge: Oat flakes 54 g (equivalent to 6 g of protein); Coconut milk 300 mL (equivalent to 0.3 g of protein); Water 150 mL; Zero calorie sugar free syrup 10 g The total energy content was equivalent to 401.74 Kcal. Participants were instructed to consume the entire meal presented to them in 15 minutes on an empty stomach when attending the study
Active Comparator: Oat porridge with potato protein; (total protein 40.6 g; of which potato protein isolate contributed 34.39 g of protein)	Dietary supplement: Potato protein isolate; Potato protein isolate, 38g (equivalent to 34.39 g of protein), was presented to participants in the form of a porridge. Other ingredients in the potato protein enriched porridge: Oat flakes 54 g (equivalent to 6 g of protein); Coconut milk 300 mL (equivalent to 0.3 g of protein); Water 150 mL; Zero calorie sugar free syrup 10 g The total energy content equiv. 401.36 Kcal. Participants were instructed to consume the entire meal presented to them in 15 minutes on an empty stomach when attending the study.
Active Comparator: Meal replacement shake; (total protein 40 g, mostly from pea protein and brown rice protein isolates)	Dietary supplement: Meal replacement shake; A meal replacement, 90 g (equivalent to 40 g of total protein), was presented to participants in the form of a shake. Other ingredients in the meal replacement shake: - Water 500 mL The total energy was equivalent to 400 Kcal Participants were instructed to consume the entire meal replacement shake presented to them in 15 minutes on an empty stomach when attending the study.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate and meal replacement shake on glucose levels (T30)	Glucose (mmol/L)	Glucose measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucose levels (T60)	Glucose (mmol/L)	Glucose measured 60 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucose levels (T120)	Glucose (mmol/L)	Glucose measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucose levels (T180)	Glucose (mmol/L)	Glucose measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on insulin levels (T30)	Insulin (pmol/L)	Insulin measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on insulin levels (T60)	Insulin (pmol/L)	Insulin measured 160 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on insulin levels (T120)	Insulin (pmol/L)	Insulin measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on insulin levels (T180)	Insulin (pmol/L)	Insulin measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucagon-like peptide 1 levels (T30)	Glucagon-like peptide 1 (pmol/L)	Glucagon-like peptide 1 measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucagon-like peptide 1 levels (T60)	Glucagon-like peptide 1 (pmol/L)	Glucagon-like peptide 1 measured 60 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucagon-like peptide 1 levels (T120)	Glucagon-like peptide 1 (pmol/L)	Glucagon-like peptide 1 measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on glucagon-like peptide 1 levels (T180)	Glucagon-like peptide 1 (pmol/L)	Glucagon-like peptide 1 measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on gastric inhibitory polypeptide (T30)	Glucagon-like peptide 1 (pmol/L)	Gastric inhibitory polypeptide measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on gastric inhibitory polypeptide (T60)	Glucagon-like peptide 1 (pmol/L)	Gastric inhibitory polypeptide measured 60 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on gastric inhibitory polypeptide (T120)	Glucagon-like peptide 1 (pmol/L)	Gastric inhibitory polypeptide measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on gastric inhibitory polypeptide (T180)	Glucagon-like peptide 1 (pmol/L)	Gastric inhibitory polypeptide measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on peptide tyrosine tyrosine levels (T30)	Peptide tyrosine tyrosine (pmol/L)	Peptide tyrosine tyrosine measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on peptide tyrosine tyrosine levels (T60) Markers: peptide tyrosine tyrosine (pmol/L)	Peptide tyrosine tyrosine (pmol/L)	Peptide tyrosine tyrosine measured 60 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on peptide tyrosine tyrosine levels (T120)	Peptide tyrosine tyrosine (pmol/L)	Peptide tyrosine tyrosine measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on peptide tyrosine tyrosine levels (T180)	Peptide tyrosine tyrosine (pmol/L)	Peptide tyrosine tyrosine measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on ghrelin levels (T30)	Ghrelin (pmol/L)	Ghrelin measured 30 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on ghrelin levels (T60)	Ghrelin (pmol/L)	Ghrelin measured 60 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on ghrelin levels (T120)	Ghrelin (pmol/L)	Ghrelin measured 120 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on ghrelin levels (T180)	Ghrelin (pmol/L)	Ghrelin measured 180 minutes post meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on appetite (T30)	Subjective analysis including: Visual Analogue Scale for Appetite (VAS-A). Scores range from 0 to 100 (the higher the score, the greater the level of appetite)	Visual Analogue Scale for Appetite (VAS-A) collected 30 minutes after meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on appetite (T60)	Subjective analysis including: Visual Analogue Scale for Appetite (VAS-A). Scores range from 0 to 100 (the higher the score, the greater the level of appetite)	Visual Analogue Scale for Appetite (VAS-A) collected 60 minutes after meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on appetite (T120)	Subjective analysis including: Visual Analogue Scale for Appetite (VAS-A). Scores range from 0 to 100 (the higher the score, the greater the level of appetite)	Visual Analogue Scale for Appetite (VAS-A) collected 120 minutes after meal consumption
To assess the acute effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on appetite (T180)	Subjective analysis including: Visual Analogue Scale for Appetite (VAS-A). Scores range from 0 to 100 (the higher the score, the greater the level of appetite)	Visual Analogue Scale for Appetite (VAS-A) collected 180 minutes after meal consumption

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
To assess the perception of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake. Subjective analysis including Visual Analogue Scale for Perception and Palatability (VAS-P).	Scores range from 0 to 100 (the higher the score, the lower the palatability)	VAS for Perception and Palatability collected immediately after meal consumption
To assess the effects of oat porridge, whey protein isolate, potato protein isolate, and meal replacement shake on food intake ad libitum, 3 hours after the intervention meal consumption.	Consecutive meal intake was assessed by measuring the weight in grams and calculating the energy content in Kcal of the food consumed.	Ad libitum food intake was assessed 3 hours post breakfast intervention meal consumption

Collaborators and Investigators

• Sponsor: University of Westminster
• Investigators: Principal Investigator: Mohammed Gulrez Zariwala, PhD, University of Westminster

Publications and helpful links

General Publications

• Khan MAB, Hashim MJ, King JK, Govender RD, Mustafa H, Al Kaabi J. Epidemiology of Type 2 Diabetes - Global Burden of Disease and Forecasted Trends. J Epidemiol Glob Health. 2020 Mar;10(1):107-111. doi: 10.2991/jegh.k.191028.001.
• Guo H, Guo Q, Li Z, Wang Z. Association between different GLP-1 receptor agonists and acute pancreatitis: case series and real-world pharmacovigilance analysis. Front Pharmacol. 2024 Nov 13;15:1461398. doi: 10.3389/fphar.2024.1461398. eCollection 2024.
• Ismail I, Hwang YH, Joo ST. Meat analog as future food: a review. J Anim Sci Technol. 2020 Mar;62(2):111-120. doi: 10.5187/jast.2020.62.2.111. Epub 2020 Mar 31.
• Monami M, Nreu B, Scatena A, Cresci B, Andreozzi F, Sesti G, Mannucci E. Safety issues with glucagon-like peptide-1 receptor agonists (pancreatitis, pancreatic cancer and cholelithiasis): Data from randomized controlled trials. Diabetes Obes Metab. 2017 Sep;19(9):1233-1241. doi: 10.1111/dom.12926. Epub 2017 Jun 20.
• Patel S. Emerging trends in nutraceutical applications of whey protein and its derivatives. J Food Sci Technol. 2015 Nov;52(11):6847-58. doi: 10.1007/s13197-015-1894-0. Epub 2015 Jun 9.
• Santesso N, Akl EA, Bianchi M, Mente A, Mustafa R, Heels-Ansdell D, Schunemann HJ. Effects of higher- versus lower-protein diets on health outcomes: a systematic review and meta-analysis. Eur J Clin Nutr. 2012 Jul;66(7):780-8. doi: 10.1038/ejcn.2012.37. Epub 2012 Apr 18.
• Zushin PH, Wu JC. Evaluating the benefits of the early use of GLP-1 receptor agonists. Lancet. 2025 Jan 18;405(10474):181-183. doi: 10.1016/S0140-6736(24)02255-4. Epub 2024 Nov 12. No abstract available.

Helpful Links

• NHS. (2023). Obesity - Treatment
• WHO. (2024). Obesity and overweight. World Health Organization.
• WHO. (2015). World health statistics 2015. World Health Organization

Study record dates

Study Major Dates

• Study Start (Actual): June 9, 2023
• Primary Completion (Actual): October 31, 2024
• Study Completion (Actual): October 31, 2024

Study Registration Dates

• First Submitted: July 29, 2025
• First Submitted That Met QC Criteria: July 29, 2025
• First Posted (Actual): August 5, 2025

Study Record Updates

• Last Update Posted (Actual): August 21, 2025
• Last Update Submitted That Met QC Criteria: August 15, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Keywords: GLP-1; appetite; insulin; supplement; satiety; glucose; ghrelin; protein; PYY; GIP; nutraceutical; whey; potato protein; rice protein; appetite hormone; pea protein
• Additional Relevant MeSH Terms: Nutrition Disorders
• Other Study ID Numbers: ETH2223-1377

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No