Obesity Risk in African American Women is Determined by a Diet-by-phenotype Interaction

NCT03499509 | Completed Results

• 2 other identifiers: IRB-300001324R01DK115483-01A1
• Study Type: interventional
• Target: 67
• Locations: 1 country
• Sites: 1

Brief Summary

The Scientific Premise of this study is that the high level of obesity displayed by African American (AA) women is due to the ability to secrete large amounts of insulin when sugary foods are consumed. When AA women eat a diet rich in starchy or sugary food (a "high-glycemic" diet that stimulates insulin secretion), the food that is eaten is stored as fat rather than being burned as fuel. The investigators previous research has suggested that AA women have an easier time losing weight and keeping it off when eating a low-glycemic diet. The proposed study will be the first randomized clinical trial to test the effect of high and low glycemic diets for weight loss and weight-loss-maintenance in obese AA women.

Conditions

Diet Modification

Outcome Measures

Primary Outcomes (1)

• Total Energy Expenditure

  Total energy expenditure measured by doubly labeled water. The protocol is based on established procedures \[12\]. Urine samples are analyzed in duplicate for H218O and 2H2O enrichments using Thermo Scientific Delta V Advantage IRMS with GasBench. CO2 production rates are determined using a fixed assumption for the dilution space ratio (1.043), using Equation 3 of Speakman et al. \[10\], and energy expenditure is calculated with equation 5 of Speakman et al. \[10\]. \[10\] Speakman JR, Yamada Y, Sagayama H et al. A standard calculation methodology for human doubly labeled water studies. Cell Rep Med 2021; 2:100203. \[12\] Goran MI, Carpenter WH, McGloin A et al. Energy expenditure in children of lean and obese parents. American Journal of Physiology 1995; 31:E917-E924. \[13\] Wolfe RR. Measurement of Total Energy Expenditure Using the Doubly-Labeled Water Method. In: Radioactive and Stable Isotope Tracers in Biomedicine. Edited by: Wiley-Liss. 1992.

  Baseline, Week 13

Study Arms (2)

Low Glycemic Diet

EXPERIMENTAL

Low Glycemic (LG) diet: The LG diet was made up of foods that do not stimulate insulin secretion and was composed of 20% CHO, 55% fat, and 25% protein. The diet emphasized complex over simple carbohydrates and allowed dairy products, fruits, and vegetables within allowance of the diet.

Other: Low Glycemic Diet

High Glycemic Diet

PLACEBO COMPARATOR

High Glycemic (HG) diet: The HG diet aligned with the United States Department of Agriculture (USDA) guidelines (http://health.gov/dietaryguidelines/2015/guidelines/) and was composed of 55% CHO, 20% fat, and 25% protein. The diet emphasized complex over simple carbohydrates and allowed dairy products, fruits, and vegetables within allowance of the diet.

Other: High Glycemic Diet

Interventions

Low Glycemic Diet OTHER

Low Glycemic (LG) diet: The LG diet was made up of foods that do not stimulate insulin secretion and was composed of 20% CHO, 55% fat, and 25% protein. The diet emphasized complex over simple carbohydrates and allowed dairy products, fruits, and vegetables within allowance of the diet.

Also known as: Low Carbohydrate Diet

Low Glycemic Diet

High Glycemic Diet OTHER

High Glycemic (HG) diet: The HG diet aligned with the United States Department of Agriculture (USDA) guidelines (http://health.gov/dietaryguidelines/2015/guidelines/) and was composed of 55% CHO, 20% fat, and 25% protein. The diet emphasized complex over simple carbohydrates and allowed dairy products, fruits, and vegetables within allowance of the diet.

Also known as: Low Fat Diet

High Glycemic Diet

Eligibility Criteria

• Age: 19 Years - 65 Years
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• BMI 30-45 kg/m2
• Sedentary to moderately active (\<2 hours/wk of moderate, structured, intentional exercise.
• Normal menstrual cycle

You may not qualify if:

• History of eating disorder
• daily use of tobacco (\>1 pack/wk)
• change in weight greater than 5 pounds in previous 3 months
• presence of any condition (e.g. PCOS) or use of any medication (e.g. glucocorticoid) deemed by the project physician to interfere with study outcomes
• applicants will be screened with a standard oral glucose tolerance test. If a participant's 2 hour glucose if \>200, they will not be able to enroll in the study.

Sponsors & Collaborators

• University of Alabama at Birmingham: lead
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): collaborator

Study Sites (1)

The University of Alabama at Birmingham

Birmingham, Alabama, 35294, United States

Location

Related Publications (1)

• Lopez Torres SY, Gower BA, Garvey WT, Martins C. Adaptive Thermogenesis After Hypocaloric Low-Carbohydrate Versus Low-Fat Diets in African American Women: A Secondary Analysis. Obesity (Silver Spring). 2025 Nov;33(11):2160-2169. doi: 10.1002/oby.70020. Epub 2025 Sep 10.

  PMID: 40931394 DERIVED

MeSH Terms

Interventions

Diet, Carbohydrate-Restricted; Diet, Fat-Restricted

Intervention Hierarchy (Ancestors)

Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Results Point of Contact

• Title: Barbara Gower, PhD
• Organization: The University of Alabama at Birmingham

bgower@uab.edu

205-934-4087

Study Officials

• Barbara Gower, PhD

  The University of Alabama at Birmingham

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: No
• Restrictive Agreement: No

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor

Study Record Dates

• First Submitted: April 4, 2018
• First Posted: April 17, 2018
• Study Start: March 19, 2019
• Primary Completion: April 30, 2024
• Study Completion: April 30, 2024
• Last Updated: May 18, 2025
• Results First Posted: May 18, 2025

Record last verified: 2025-05

Locations

US (1)