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.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
OTHER
Masking
NONE
Enrollment
30
Roux-en-Y gastric bypass surgery will be performed with post-weight loss testing performed after \~16-18% weight loss is achieved.
Subjects will meet with a dietitian and/or behaviorist over 4-6 months to lose \~16-18% of their body weight.
Beth Henk
St Louis, Missouri, United States
Postprandial plasma insulin kinetics
Plasma insulin kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial plasma insulin kinetics
Plasma insulin kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial glucose kinetics
Plasma glucose kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial glucose kinetics
Plasma glucose kinetics will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
β-cell function
β-cell function will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
β-cell function
β-cell function will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial triglyceride concentrations
Plasma triglyceride concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial triglyceride concentrations
Plasma triglyceride concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial non-esterified fatty acid concentrations
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.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial non-esterified fatty acid concentrations
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.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial hormone concentrations
Plasma hormone concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial hormone concentrations
Plasma hormone concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial cytokine concentrations
Plasma cytokine concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial cytokine concentrations
Plasma cytokine concentrations will be assessed in blood samples collected before and after consuming a standard-carbohydrate or a low-carbohydrate meal.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial lipids
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.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial lipids
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.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Postprandial metabolites
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.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Postprandial metabolites
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.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
Transcriptome in adipose tissue
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.
Time frame: Baseline only (cross-sectional comparison of metabolic responses in African American and non-Hispanic White adults with obesity)
Transcriptome in adipose tissue
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.
Time frame: After 16-18% weight loss induced by LCD or RYGB (~4-6 months)
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