Metabolic Adaptations to High-fat Diet

NCT06537401 | Terminated

• 1 other identifier: NCR245732
• Study Type: interventional
• Target: 2
• Locations: 1 country
• Sites: 1

Brief Summary

The purpose of this study is to understand how the body's response after a meal is influenced by insulin and sugar in the blood. The primary question this study seeks to address is what is the effect of reduced insulin sensitivity on postprandial metabolic flexibility to an oral glucose tolerance test. We will recruit 50 adults (ages 20-45; 50% female) who are otherwise healthy (no known clinical diagnosis) into our non-randomized crossover trial to determine the effect of changes in insulin sensitivity on metabolic response to feeding. Insulin sensitivity will be decreased using a three-day high-fat diet (HFD) with extra calories. Whole-body metabolism will be measured during a standard 75-gram oral glucose tolerance test (OGTT). Metabolic response to feeding (e.g. OGTT) will be compared before and after the HFD and compared with the control diet to understand the effect of decreased insulin sensitivity on the metabolic response to feeding. The role of biological sex as a moderator of the effect of increased insulin resistance on postprandial metabolic flexibility will also be investigated

Conditions

Adiposity; Insulin Sensitivity; Impaired Glucose Tolerance; Metabolic Disturbance

Keywords

Metabolism; Feeding; Substrate Oxidation; Metabolic Flexibility; High Fat Diet; Insulin Sensitivity

Outcome Measures

Primary Outcomes (1)

• Postprandial Metabolic Flexibility

  Mean difference respiratory exchange ratio during an oral glucose tolerance test following a high fat diet

  3 Days

Study Arms (1)

Hypercaloric, High Fat Diet

EXPERIMENTAL

For three calendar days participants will be asked to track all foods they eat and beverages they drink (habitual diet) in a mobile application. Following the three days following the habitual diet, participants will consume 165% of their estimated daily energy needs with 65% of those calories coming from fat.

Behavioral: Hypercaloric, High Fat Diet

Interventions

Hypercaloric, High Fat Diet BEHAVIORAL

Participants will select meals from a list of sample breakfast, lunch, and dinner options from grocery stores. Typical intake will be estimated as 160-170% of resting metabolic rate, which will then be multiplied by 1.65 as the target calorie intake for the HFD. Target fat intake will be 65% of the HFD calorie target. To ensure participants will achieve the desired calorie and fat intake, they will also be provided with pre-made nutrient shakes and half-and-half. Participants will supplement their food intake with one to three shakes per day for each of the three days, depending on the fat and calorie content of the foods they select. They will be asked to add half-and-half equally between across the shakes.

Hypercaloric, High Fat Diet

Eligibility Criteria

• Age: 20 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Males or Females between the ages of 20 and 45 years
• Body mass index (BMI) of 18.5-29.9 kg/m2
• Low risk for medical complications as determined by physical activity readiness questionnaire (PARQ).
• Low risk for food insecurity via the Hunger Vital Sign screener

You may not qualify if:

• Currently taking any antioxidant supplementation, prescription non-steroidal anti- inflammatory drugs, antibiotics, steroids, probiotics, medications for management of cholesterol, diabetes, body weight/obesity, or are undergoing transgender hormone therapy.
• Currently pregnant (verified by urine pregnancy test)
• Any history of disordered eating (i.e., anorexia nervosa, bulimia nervosa, binge eating disorder, etc.) or high risk for disordered eating via validated questionnaire (SCOFF)
• Any history of gastrointestinal diseases (i.e., gastroesophageal reflux disease, irritable bowel syndrome, Celiac disease, Crohn's disease, or lactose intolerance)
• Allergies to wheat or gluten, milk, soy, tree nuts (e.g., almonds, walnuts, pecans), or peanuts.
• Followed a ketogenic diet within the last three months
• Instructed by a medical provided to avoid a high-fat diet due to cardiovascular disease risk.
• Cardiorespiratory fitness (VO2max) greater than the 90th percentile for age and sex

Sponsors & Collaborators

• George Washington University: lead

Study Sites (1)

George Washington University School of Public Health

Washington D.C., District of Columbia, 20052, United States

Location

MeSH Terms

Conditions

Obesity; Insulin Resistance; Glucose Intolerance

Interventions

Diet, High-Fat

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Hyperinsulinism; Glucose Metabolism Disorders; Metabolic Diseases; Hyperglycemia

Intervention Hierarchy (Ancestors)

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

Study Officials

• Matthew D Barberio, PhD

  George Washington University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Assistant Professor, Department of Exercise and Nutrition Science

Model Details: Non-Randomized Crossover

Study Record Dates

• First Submitted: August 1, 2024
• First Posted: August 5, 2024
• Study Start: August 12, 2024
• Primary Completion: December 31, 2024
• Study Completion: December 31, 2024
• Last Updated: August 26, 2025

Record last verified: 2025-08

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)