Stable Isotopes for Obesity

(Si-OBA Trial)

Overseen By Gena L Irwin (Research Assistant), M.S

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Illinois at Urbana-Champaign

Disqualifiers: Pregnancy, Food allergies, Smoker, Metabolic diseases, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 3

8 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to study how the body processes calories and sugar using special markers called stable isotopes. Participants will try two different drink routines: one with multiple small calorie drinks and another with a single glucose (sugar) drink. Researchers will collect samples, such as blood and breath, to observe the effects of these drinks on the body. The study seeks individuals considered obese, with a waist size of at least 102 cm for men or 88 cm for women, who lead a mostly inactive lifestyle. As an unphased trial, it offers participants the opportunity to contribute to important research on metabolism and obesity.

Do I need to stop my current medications for the trial?

The trial information does not specify whether you need to stop taking your current medications. It's best to discuss this with the trial coordinators.

What prior data suggests that these stable isotope methods are safe for participants?

A previous study found the Indicator Amino Acid Oxidation (IAAO) method to be minimally invasive, making it gentle on participants. This method helps researchers understand nutrient needs with minimal discomfort and has been used safely in similar studies.

Research shows that the Stable Isotope Oral Glucose Tolerance Test (SI-OGTT) is a sensitive and cost-effective tool. It measures how the body processes glucose, particularly in individuals with obesity. Designed for safety, the test has been used in various studies without major side effects.

Both methods have been tested in scientific research and are well-tolerated, typically not causing strong negative reactions in participants. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about these treatments for obesity because they explore innovative ways to understand and potentially manage the condition. The Indispensable Amino Acid Oxidation (IAAO) method uses stable isotopes to study how amino acids are metabolized in the body, offering insights that could lead to personalized nutrition strategies. Meanwhile, the Stable Isotope Oral Glucose Tolerance Test (SIOGTT) provides a detailed look at glucose metabolism, which might reveal new angles for addressing insulin sensitivity. Unlike standard treatments that often focus on diet, exercise, or medication, these techniques aim to uncover the metabolic nuances of obesity, paving the way for more targeted interventions.

What evidence suggests that this trial's treatments could be effective for obesity?

This trial will compare two methods: the Indicator Amino Acid Oxidation (IAAO) method and the Stable Isotope Oral Glucose Tolerance Test (SI-OGTT). Research has shown that the IAAO method determines protein needs by assessing how well the body uses amino acids, the building blocks of protein. If one amino acid is missing, the body cannot use the others effectively, leading to waste. This method identifies and addresses gaps in protein intake, enhancing overall nutrition.

Meanwhile, studies have also shown that the SI-OGTT is useful for understanding how the body handles sugar. It measures how the body processes glucose and insulin, which is important for people with obesity. This test is sensitive and cost-effective, making it a valuable tool for studying how the body manages sugar in everyday life. ^{6 7 8 9 10}

Are You a Good Fit for This Trial?

This trial is for adults aged 19-59 who are obese, with a body mass index (BMI) of 30 or higher and waist circumference over 102 cm for males or over 88 cm for females. Participants should also have low physical activity levels as indicated by scoring less than 14 units on the Godin Leisure-time Exercise Questionnaire.

Inclusion Criteria

* 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

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Virtual screening and questionnaires

Preliminary Testing

Participants undergo preliminary testing including urine, blood, breath, and muscle biopsies after an overnight fast

1 day

1 visit (in-person)

IAAO Experimental Arm

Participants ingest a series of 6 hourly beverages containing stable isotopes for metabolic assessment

6.5 hours

1 visit (in-person)

SIOGTT Experimental Arm

Participants consume a glucose drink with stable isotopes for glucose tolerance assessment

3 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

1 week

What Are the Treatments Tested in This Trial?

Interventions

• Indispensable Amino Acid Oxidation
• Stable Isotope Oral Glucose Tolerance Test

Trial Overview The study tests how indispensable amino acids and glucose metabolism work in people with obesity using stable isotopes. It's a crossover trial where participants first take multiple drinks containing isotopes throughout the day, then switch to one drink with labeled glucose, monitoring effects via blood, breath, urine, and muscle samples.

How Is the Trial Designed?

Group I: SIOGTT Experimental Treatment 1 Intervention

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

Group II: IAAO Experimental Treatment 1 Intervention

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

Who Is Running the Clinical Trial?

University of Illinois at Urbana-Champaign

Lead Sponsor

Trials

203

Recruited

40,600+

Citations

1. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC7844655/

Estimation of inter-individual variability of protein ... The indicator amino acid oxidation (IAAO) method is a recently developed method to determine the protein requirement and is particularly useful for analyzing ...

2. sciencedirect.com sciencedirect.com/science/article/pii/S0022316623725297

Evaluation of protein requirements using the indicator ... The indicator amino acid oxidation (IAAO) method has been accepted as an approach to evaluate habitual protein requirements under free-living conditions.

3. ajcn.nutrition.org ajcn.nutrition.org/article/S0002-9165(23)02834-4/fulltext

Protein requirements and the indicator amino acid oxidation ... An inadequate, limiting intake of the test amino acid leads to inefficient utilization of all other amino acids and hence their high rates of oxidation. As the ...

4. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC11148338/

Metabolic availability of amino acids in humans - PMC The results demonstrate that protein complementation augments the limiting amino acid supply and increases protein synthesis. Keywords: protein ...

5. researchgate.net researchgate.net/publication/394217028_The_indicator_amino_acid_oxidation_IAAO_technique_a_novel_approach_to_assess_protein_intakes_that_maximize_whole-body_protein_anabolism

(PDF) The indicator amino acid oxidation (IAAO) technique We conclude that the current IAAO method represents a minimally invasive technique allowing elegant within-subject designs to assess the maximal ...

6. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC12346589/

Current Data on the Role of Amino Acids in the Management ... Although clinical studies indicate that changes in dietary amino acids could lead to modest weight loss, improved metabolic profiles, and ...

7. sciencedirect.com sciencedirect.com/science/article/pii/S2212877821002489

Impacts of essential amino acids on energy balance Alterations in dietary EAA intake can reduce fat mass and body weight. Increased circulating BCAAs have been observed in obese human and animal models.

8. nature.com nature.com/articles/s41392-023-01569-3

Amino acid metabolism in health and disease Therapeutically targeting tumor cell metabolism have been proven effective with fewer side effects compared to some conventional treatments.

9. translational-medicine.biomedcentral.com translational-medicine.biomedcentral.com/articles/10.1186/s12967-023-04833-w

Dietary sulfur amino acid restriction in humans with ... Our study shows that SAAR leads to greater weight loss, decreased leptin and increased ketone bodies compared to controls.

10. tandfonline.com tandfonline.com/doi/full/10.1080/10408398.2025.2541895

The indicator amino acid oxidation (IAAO) technique We conclude that the current IAAO method represents a minimally invasive technique allowing elegant within-subject designs to assess the maximal ...