Stable Isotopes- Adults With Obesity

NCT07020741 | Recruiting

• 2 other identifiers: IRB25-0166RB25064
• Study Type: interventional
• Target: 8
• Locations: 1 country
• Sites: 1

Brief Summary

In a crossover design, 8 participants will receive caloric drinks containing stable isotopes. In one arm of the study, participants will consume 6 hourly drinks containing two stable isotopes. Repeated blood, breath, urine, and muscle biopsies will be taken. In the second arm, participants will consume 1 drink containing 75g glucose, labeled with two stable isotopes of glucose. Periodic blood and breath will be taken over three hours.

Conditions

Protein Metabolism; Obese Patients (BMI ≥ 30 kg/m²); Glucose Metabolism

Outcome Measures

Primary Outcomes (2)

• Define obesity-related whole body protein efficiency based of the IAAO method

  Amino Acid Oxidation of phenylalanine will be measured using the IAAO method by periodic ingestion of amino acid mixture. Trials will start at \~7:00 am (-30 minutes) with a total duration of 6.5 hours (390 minutes) Measurements of breath (-30, 0, 120, 240, 270, 300, 330 and 360 minutes), Urine (-30, 0, 240, 300, and 360 minutes), muscle biopsy (-30 and 360 minutes) and blood (-30, 0, 30, 60, 90,120, 180, 240, 300, and 360 minutes) will be used to determine the whole body efficiency of protein in obese populations.

  0 - 6 hours observational period ingesting six hourly meals, within 1 week of preliminary testing. Baseline measures taken at --30 minutes.

• Assessment of oral glucose tolerance based on a dual tracer technique

  Measure glucose kinetics via \[13C\] and D5 Glucose over 3 hours to determine glucose tolerance. Trials will start at \~7:00 am (-10 minutes) and last \~ 3 hours. (190 minutes)

  0- 3 hour observational period. Within 1 week of the prospective arm. Baseline taken at -30 minutes.

Study Arms (2)

IAAO

EXPERIMENTAL

Participants will ingest a series of 6 hourly beverages containing 50% of the daily intake of 1.1g/kg/day

Procedure: Indispensable Amino Acid Oxidation

SIOGTT

EXPERIMENTAL

Participants will consume one 75g glucose drink dissolved in 250 ml of water.

Procedure: Stable Isotope Oral Glucose Tolerance Test

Interventions

Indispensable Amino Acid Oxidation PROCEDURE

Participants will ingest six hourly meals designed to provide 50% of the daily intake of 1.1 g·kgLBM. Additional energy (1.5x daily resting metabolic rate), carbohydrate (55%), and fat (35%) will be provided in beverages and protein-free cookies (for palatability). The first drink will contain priming doses of NaH13CO2 (0.176 mg·kg-1), \[13C\]phenylalanine (1.86 mg·kg-1), \[2H5\]phenylalanine (0.34 mg·kg-1) with all subsequent drinks containing 1.2 mg·kg-1 \[13C\]phenylalanine and 0.51 mg·kg-1 \[2H5\]phenylalanine.

Also known as: IAAO

IAAO

Stable Isotope Oral Glucose Tolerance Test PROCEDURE

Participants will consume a 75g glucose drink dissolved in 250 ml of water enriched with \[6,6\_2H2\]glucose and \[13C6\]glucose.

Also known as: Si OGTT

SIOGTT

Eligibility Criteria

• Age: 19 Years - 59 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• ages 19-59
• Obese \>/= 30 kg/m\^2 and \>/= 102 cm for males and \>/= 88 cm for females
• Godin Leisure-time or exercise questionnaire \<14 units

You may not qualify if:

• Pregnant or become pregnant
• Any known food allergies
• Smoker
• Are physically active
• Have any known metabolic diseases
• Have been weight unstable within the last 6 months (lost or gained \>10% of body mass)
• Non eumenorrheic or on a hormonal birth control

Sponsors & Collaborators

• University of Illinois at Urbana-Champaign: lead

Study Sites (1)

Freer Hall - University of Illinois

Urbana, Illinois, 61801, United States

RECRUITING

Central Study Contacts

Nicholas Burd (Associate Professor), PhD

CONTACT

2172440970; naburd@illinois.edu

Gena L Irwin (Research Assistant), M.S

CONTACT

3608883281; genai2@illinois.edu

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: The study will employ a crossover model where they will complete 2 of 2 conditions, in a randomized order.

Study Record Dates

• First Submitted: May 9, 2025
• First Posted: June 13, 2025
• Study Start: September 12, 2025
• Primary Completion (Estimated): August 30, 2026
• Study Completion (Estimated): December 31, 2026
• Last Updated: April 29, 2026

Record last verified: 2025-06

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)