Recruiting

Caloric Dose

Sponsor:

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Code:

NCT06223555

Conditions

Obesity

Healthy Volunteer

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

Interventions

Fixed Mixed Meal Test

Adjusted Mixed Meal Test

Study Details

Brief summary:

Background:

Researchers use mixed meal tolerance tests (MMTTs) to look at how people s bodies respond to eating a meal. However, researchers do not agree on how to decide the number of calories to give in each meal. Some use fixed meals, which are the same size for everyone, and some use adjusted meals, based on the size of the person s body. Researchers want to know which MMTT is best to use for future research.

Objective:

To learn how fixed vs adjusted meals affect blood glucose levels in healthy people.

Eligibility:

Healthy people aged 18 years or older.

Design:

Participants will have 3 or 4 clinic visits of up to 8 hours in 8 weeks.

Participants will have baseline tests:

Their height, weight, and waist size will be measured.

They will have an oral glucose tolerance test: A needle attached to a tube (IV) will be inserted into a vein in the arm. They will have a sugary drink. Blood samples will be taken from the tube at intervals up to 3 hours after the drink.

They will have a body scan.

Participants will have 2 MMTT visits. One will include a fixed meal and one will include an adjusted meal. They will have tests at both visits:

Resting metabolic rate: A clear hood will be placed over the participant s head while they rest for 20 minutes. This will measure the oxygen they breathe in and out.

MMTT. Participants will have 5 minutes to drink a liquid meal. Blood samples will be taken at intervals for the next 4 hours....

Conditions

Obesity

Healthy Volunteer

Study ID

NCT06223555

Start date

Aug 23, 2024

Status verified date

Aug 14, 2026

Completion date

Dec 31, 2027

Anticipated

Primary completion date

Jun 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 70+

Healthy Volunteers: Accepted

  • INCLUSION CRITERIA:

In order to be eligible to participate in this study, an individual must meet all of the following criteria:

  • Provision of signed and dated informed consent form.
  • Agreement to adhere to Lifestyle Considerations throughout study duration.
  • Males and females; Age >= 18years
  • Healthy, as determined by medical history, physical examination, and laboratory tests.

EXCLUSION CRITERIA:

An individual who meets any of the following criteria will be excluded from participation in this

study:

  • Current use of medications, dietary supplements, or alternative therapies known to alter energy metabolism.
  • Fasting plasma glucose >= 126 mg/dL
  • Type I or Type II Diabetes Mellitus by self-report.
  • Hematologic disorders including significant anemia (male hemoglobin < 13.0 g/dL or female hemoglobin < 11.0 g/dL)
  • Current pregnancy, pregnancy within the past 6 months or currently lactating
  • History or self-report of gastrointestinal disease, including inflammatory bowel diseases (e.g. Chron s disease and ulcerative colitis), malabsorption syndromes (e.g. celiac disease), gastric ulcer (active) which may alter metabolism or absorption of study food by self-report
  • Evidence of alcohol abuse as defined by an 8-point score on the Alcohol consumption screening AUDIT questionnaire in adults.
  • Participants who report taking large doses of acetaminophen (> 3 grams daily) who cannot stop acetaminophen 24 hours prior to and following the meal tests will be excluded from the study.
  • Inability to consume provided food based on a food allergy or intolerance.
  • Conditions not specifically mentioned above may serve as criteria for exclusion at the discretion of the investigators.
  • Any disorder, unwillingness, or inability not covered by any other exclusion criteria which, in the investigator s and/or team s opinion, jeopardizes the safety of the participant or others or would interfere with adherence to the protocol (such as claustrophobia).

Conditions not specifically mentioned above may serve as criteria for exclusion at the discretion of the investigators.

Study Design

Enrollment

79 participants

Anticipated

Allocation

Randomized

Intervention Model

Crossover

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

active comparator: 1

Fixed Mixed Meal Test

active comparator: 2

Adjusted Mixed Meal Test

Interventions

Fixed Mixed Meal Test

a FIXED dose meal that will be 900 kcal of a liquid meal

Adjusted Mixed Meal Test

a body weight ADJUSTED dose liquid meal.

(30% of total daily energy requirements)

Primary outcome measure

  • To determine whether an adjusted energy dose MMTTor a fixed dosed meal will result in greater variability in glucose area under the curve (AUC) within the same participants across a range of BMIs. [ Time Frame: Baseline, Visit 3/4 ]

Central Contacts and Locations

Central contacts

Susanne M Votruba, Ph.D.

(301) 827-3521votrubas@niddk.nih.gov

Locations

NIDDK, Phoenix

Recruiting

Phoenix, Arizona, United States, 85014

Contacts

Susi Votruba, Ph.D.

602-200-5336votrubas@niddk.nih.gov

More Information

Sponsor

National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)

Last update posted

Aug 18, 2026

Last verified

Aug 14, 2026

Keywords

  • Healthy Volunteer
  • Obesity
  • Body Composition
  • Diet
  • Mixed Meal Test
  • Glucose

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) on 2026-08-18.