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NCT Number: NCT03091725

Postprandial Nutrient Homeostasis Before and After Weight Loss Induced by Low-calorie Diet or RYGB

The purpose of this study is to compare the metabolic responses to low-carbohydrate and standard-carbohydrate meals in African Americans and non-Hispanic White adults with obesity and the effect of weight loss induced by low-calorie diet (LCD) or Roux-en-Y gastric bypass (RYGB) on the metabolic responses to low-carbohydrate and standard meals. Participants will consume: 1) a standard-carbohydrate meal (~49 g glucose) and 2) a low-carbohydrate (~3.4 g glucose) meal on separate study visits performed in a randomized order. We will evaluate the meals' effect before and after ~16-18% weight loss on postprandial i) insulin kinetics, ii) glucose kinetics iii) β-cell function; iv) plasma triglyceride and non-esterified fatty acid concentrations; v) plasma hormone concentrations; vi) plasma cytokine concentrations; vi) plasma metabolomics; and vii) adipose tissue transcriptomics.

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Key information

Conditions

Obesity Body Weight Nutrition Disorders Nutritional and Metabolic Diseases Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

25 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Beth Henk

St Louis, Missouri, 63110, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Surgery Group (RYGB):

  • Males and Females
  • Scheduled for RYGB surgery
  • Body Mass Index 35-60 kg/m²
  • Without Type 2 Diabetes (T2D)

LCD group:

  • Males and Females
  • Body Mass Index 35-60 kg/m²
  • Without Type 2 Diabetes (T2D)

Exclusion criteria

  • Regular use of tobacco products
  • Previous intestinal resection
  • Pregnant or breastfeeding
  • Evidence of significant organ system dysfunction or disease other than obesity and T2D
  • Use of any medication that might, in the opinion of the investigator, affect metabolic function
  • Exercise ≥90 minutes per week
  • Use or past use of hormone replacement therapy within the past 6 months

Treatment and study plan

Roux-en-Y gastric bypass surgery

Procedure

Roux-en-Y gastric bypass surgery will be performed with post-weight loss testing performed after ~16-18% weight loss is achieved.

Low-calorie diet

Behavioral

Subjects will meet with a dietitian and/or behaviorist over 4-6 months to lose ~16-18% of their body weight.

Primary outcomes

  1. Postprandial plasma insulin kinetics

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma insulin kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  2. Postprandial plasma insulin kinetics

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma insulin kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

Secondary outcomes

  1. Postprandial glucose kinetics

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma glucose kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  2. Postprandial glucose kinetics

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma glucose kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  3. β-cell function

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    β-cell function will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  4. β-cell function

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    β-cell function will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  5. Postprandial triglyceride concentrations

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma triglyceride concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  6. Postprandial triglyceride concentrations

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma triglyceride concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  7. Postprandial non-esterified fatty acid concentrations

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma non-esterified fatty acid concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  8. Postprandial non-esterified fatty acid concentrations

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma non-esterified fatty acid concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  9. Postprandial hormone concentrations

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma hormone concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  10. Postprandial hormone concentrations

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma hormone concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  11. Postprandial cytokine concentrations

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma cytokine concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  12. Postprandial cytokine concentrations

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma cytokine concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.

  13. Postprandial lipids

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma lipids will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal by using mass spectrometry.

  14. Postprandial lipids

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma lipids will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal by using mass spectrometry.

  15. Postprandial metabolites

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    Plasma metabolites will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal by using mass spectrometry.

  16. Postprandial metabolites

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    Plasma metabolites will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal by using mass spectrometry.

  17. Transcriptome in adipose tissue

    Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)

    The transcriptome (all RNA that are responsible for making proteins from DNA templates) will be evaluated by using RNA sequencing techniques in adipose tissue samples collected before and ~3h after consuming a standard-carbohydrate or a low-carbohydrate meal.

  18. Transcriptome in adipose tissue

    Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)

    The transcriptome (all RNA that are responsible for making proteins from DNA templates) will be evaluated by using RNA sequencing techniques in adipose tissue samples collected before and ~3h after consuming a standard-carbohydrate or a low-carbohydrate meal.

Sponsors and collaborators

Lead sponsor

Washington University School of Medicine

Other

Collaborators

  • Kilo Diabetes & Vascular Research Foundation

Registry information

Acronym: FGB

Important dates

Study start
2017
Primary completion
2026
Study completion
2026
First posted
Mar 27, 2017
Registry last updated
Mar 17, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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