Ultra-Processed Foods, Palatability, Appetite, and Gastrointestinal Transit

Ultra-Processed Foods - Palatability and Appetite

The goal of this clinical trial is to learn how food processing level affects appetite and gastrointestinal transit time when meal palatability is changed. Participants will complete one screening visit and four test visits. During each test visit, participants will consume one of four meals that differ by food processing level and palatability: high-palatability ultra-processed food, low-palatability ultra-processed food, high-palatability non-ultra-processed food, or low-palatability non-ultra-processed food. The main questions this study aims to answer are whether food processing and palatability affect appetite sensations and gastrointestinal transit time. Participants will rate appetite sensations during each test visit and provide breath samples to measure gastrointestinal transit time.

Study Overview

• Status: Completed
• Conditions: Eating Behavior; Appetite; Gastrointestinal Transit; Food Processing; Food Palatability
• Intervention / Treatment: Other: Palatable Ultra-Processed Food Meal; Other: Unpalatable Ultra-Processed Food Meal; Other: Palatable Non-Ultra-Processed Food Meal; Other: Unpalatable Non-Ultra-Processed Food Meal

Detailed Description

This is a randomized crossover trial examining the effects of food processing level and palatability on appetite and gastrointestinal transit time. Participants will complete a screening visit followed by four test visits, with each test visit separated by at least one week. Each participant will consume all four test meals: high-palatability ultra-processed food, low-palatability ultra-processed food, high-palatability non-ultra-processed food, and low-palatability non-ultra-processed food. Palatability will be reduced by adding bitter melon powder to the low-palatability meals. During each test visit, participants will consume the assigned test meal containing lactulose as a marker of gastrointestinal transit time. Breath samples will be collected to assess orocecal transit time using hydrogen analysis. Participants will also rate meal palatability and appetite sensations, including hunger, fullness, desire to eat, amount they could eat, and thirst, using visual analog scales during the test visit.

• Study Type: Interventional
• Enrollment (Actual): 40
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Indiana
    • West Lafayette, Indiana, United States, 47907
      • Purdue University

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria:

• Individuals aged 18 to 60 years.
• Any sex, gender, or orientation.
• Self-reported good health.
• No medication use.
• No allergies or food sensitivities to any of the foods used in the study.
• No anticipated change in physical activity during the study period.
• Willingness to complete all planned study activities, including the screening visit and four test visits.
• At screening, participants must rate the selected high-palatability foods between 60 and 90 on a 100-unit visual analog scale, where 100 = extremely palatable.
• At screening, participants must rate the selected low-palatability foods between 10 and 40 on a 100-unit visual analog scale.

Exclusion Criteria:

• Younger than 18 years or older than 60 years.
• Current medication use.
• Allergies or food sensitivities to any study foods.
• Not meeting the required palatability rating ranges during screening.
• Anticipated change in physical activity during the study period.
• Not self-reporting good health.
• Unwillingness or inability to complete the planned study activities.

Study Plan

How is the study designed?

Design Details

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

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Palatable Ultra-Processed Food; Participants will consume a palatable ultra-processed test meal during one study visit. The meal will be used to assess appetite sensations, palatability ratings, and gastrointestinal transit time.	Other: Palatable Ultra-Processed Food Meal; Participants will consume a palatable ultra-processed test meal during one study visit. The meal will consist of commonly available ultra-processed food items and will be used to assess appetite sensations, meal palatability, and gastrointestinal transit time.
Experimental: Unpalatable Ultra-Processed Food; Participants will consume an unpalatable ultra-processed test meal during one study visit. Palatability will be reduced by adding bitter melon powder. The meal will be used to assess appetite sensations, palatability ratings, and gastrointestinal transit time.	Other: Unpalatable Ultra-Processed Food Meal; Participants will consume an unpalatable ultra-processed test meal during one study visit. Palatability will be reduced by adding organic bitter melon powder to the ultra-processed meal. The meal will be used to assess appetite sensations, meal palatability, and gastrointestinal transit time.
Experimental: Palatable Non-Ultra-Processed Food; Participants will consume a palatable non-ultra-processed test meal during one study visit. The meal will be used to assess appetite sensations, palatability ratings, and gastrointestinal transit time.	Other: Palatable Non-Ultra-Processed Food Meal; Participants will consume a palatable non-ultra-processed test meal during one study visit. The meal will consist of commonly available non-ultra-processed food items and will be used to assess appetite sensations, meal palatability, and gastrointestinal transit time.
Experimental: Unpalatable Non-Ultra-Processed Food; Participants will consume a unpalatable non-ultra-processed test meal during one study visit. Palatability will be reduced by adding bitter melon powder. The meal will be used to assess appetite sensations, palatability ratings, and gastrointestinal transit time.	Other: Unpalatable Non-Ultra-Processed Food Meal; Participants will consume an unpalatable non-ultra-processed test meal during one study visit. Palatability will be reduced by adding organic bitter melon powder to the non-ultra-processed meal. The meal will be used to assess appetite sensations, meal palatability, and gastrointestinal transit time.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Orocecal Transit Time	Orocecal transit time will be assessed using hydrogen analysis of end-alveolar breath samples collected after consumption of each test meal. Each test meal will contain lactulose as a marker of gastrointestinal transit time.	During each test visit, up to 4.5 hours after meal consumption
Appetite Sensations	Appetite sensations, including hunger, fullness, desire to eat, amount participants could eat, and thirst, will be assessed using visual analog scales during each test visit after consumption of the assigned test meal every 30 minutes	During each test visit, up to 4.5 hours after meal consumption
Meal Palatability Ratings	Meal palatability will be assessed using participant ratings of the appeal of each test meal during each study visit.	During each test visit, up to 4.5 hours after meal consumption

Collaborators and Investigators

• Sponsor: Purdue University

Publications and helpful links

General Publications

• Hall KD, Ayuketah A, Brychta R, Cai H, Cassimatis T, Chen KY, Chung ST, Costa E, Courville A, Darcey V, Fletcher LA, Forde CG, Gharib AM, Guo J, Howard R, Joseph PV, McGehee S, Ouwerkerk R, Raisinger K, Rozga I, Stagliano M, Walter M, Walter PJ, Yang S, Zhou M. Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake. Cell Metab. 2019 Jul 2;30(1):67-77.e3. doi: 10.1016/j.cmet.2019.05.008. Epub 2019 May 16.

Study record dates

Study Major Dates

• Study Start (Actual): September 24, 2024
• Primary Completion (Actual): April 30, 2026
• Study Completion (Actual): April 30, 2026

Study Registration Dates

• First Submitted: May 14, 2026
• First Submitted That Met QC Criteria: May 14, 2026
• First Posted (Actual): May 20, 2026

Study Record Updates

• Last Update Posted (Actual): May 20, 2026
• Last Update Submitted That Met QC Criteria: May 14, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Appetite; Palatability; Ultra-processed foods; Lactulose; Visual analog scale; Non-ultra-processed foods; Gastrointestinal transit time; Orocecal transit time; Hydrogen breath test; Bitter melon powder
• Additional Relevant MeSH Terms: Behavior; Behavior, Animal; Feeding Behavior
• Other Study ID Numbers: IRB-2024-450

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared because the current IRB-approved protocol does not include a formal plan for external individual participant data sharing. Study data will be de-identified for analysis, and identifying information will be stored separately from study data. Code numbers linking participants to their data will be destroyed according to the approved protocol. No information by which participants can be identified will be released or published.

Drug and device information, study documents

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