Recruiting

Observational Study

Sponsor:

Pennington Biomedical Research Center

Code:

NCT06309576

Conditions

Obesity

Underweight

Eligibility Criteria

Sex: All

Age: 18 - 40

Healthy Volunteers: Accepted

Interventions

Fasting-refeeding cycle

Study Details

Brief summary:

The regulation of human body weight and fatness is not fully understood. Although some models of regulation have been proposed (set point, dual-intervention point, others), no studies have been designed to test their predictions. In this pilot and feasibility study, the investigators will implement an experimental approach to test the predictions of models of body weight regulation in humans. Men and women with either low body weight or obesity will be exposed to a 2-day fasting followed by a 2-day ad-libitum refeeding. During the entire fasting-refeeding period, energy intake and expenditure will be accurately measured within metabolic chambers. The investigators will therefore determine the compensatory responses to fasting elicited to prevent weight loss. The results will serve to design and power future studies to better understand body weight regulation.

Conditions

Obesity

Underweight

Study ID

NCT06309576

Start date

Jan 17, 2025

Status verified date

May, 2026

Completion date

Dec 3, 2026

Anticipated

Primary completion date

Oct 1, 2026

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 18 - 40

Healthy Volunteers: Accepted

Inclusion Criteria:

  • Body mass index lower than 20 kg/m2 for the low body weight group, or 30 kg/m2 or greater for the obesity group
  • 18-40 years old
  • Nulliparous and regular menstrual cycle (25-35 days) during the last six months (in women)
  • Normal thyroid function, blood count, and chemistry 15 panel (normal plasma glucose will be considered at <100 mg/dL; normal serum HDL cholesterol at >=50 mg/dL for women and >=40 mg/dL for men; and normal serum triglycerides at <150 mg/dL).
  • Self-reported weight stability during the last six months (±3 kg)
  • Rate the liking of at least one of the flavored liquid meals (Ensure Plus, Abbot Nutrition) between 5 and 8 on a 9-point Likert scale
  • Willing to only drink up to two assigned flavors of Ensure Plus for two consecutive days

Exclusion Criteria:

  • Eating disorders as indicated by a global score ≥2.80 in the Eating Disorder Examination Questionnaire, or a previous diagnosis of an eating disorder
  • For the low body weight group, having food insecurity (with or without hunger) as assessed by the USDA
  • Recreational moderate-intensity physical activity ≥150 min/week, recreational vigorous-intensity physical activity ≥75 min/week, or a combination of recreational moderate-intensity and vigorous-intensity physical activity (moderate time + \[2 × vigorous time\]) ≥150 min/week as assessed by the Global Physical Activity Questionnaire, or being a professional athlete
  • Cigarette or vape smoking
  • Intake of more than 14 alcoholic drinks per week
  • Use of medications that may affect energy intake and/or expenditure, for example, semaglutide, liraglutide, exenatide, other GLP-1 receptor agonists, phentermine-topiramate, naltrexone-bupropion, orlistat, metformin, SGLT2 inhibitors, pramlintide, levocarnitine, amphetamines, and amphetamine-like drugs
  • Human immunodeficiency virus, galactosemia, and lactose intolerance
  • Diseases that affect energy homeostasis including endocrine such as hypo/hyperthyroidism, or type 1 or 2 diabetes; cancer; chronic pulmonary diseases; cardiovascular disease; and renal disease
  • History of inflammatory bowel disease (ulcerative colitis, Crohn's), malabsorption syndromes (intestinal, pancreatic), and sprue or gluten intolerance
  • Having moderate to severe sleep apnea defined as an oxygen desaturation index \&gt;10 times/hour assessed by overnight oximetry to be conducted on the night following the screening visit
  • Use of oral hormonal contraceptives or less than 6 months using a hormonal intrauterine device (in women)
  • Adults who are unable to consent
  • Prisoners
  • Currently pregnant or breastfeeding (in women)

Study Design

Enrollment

12 participants

Anticipated

Intervention Model

Single group

Primary purpose

Basic Science

Interventions and Outcome Measures

Arms

experimental: Fasting-refeeding cycle

Participants will be maintained in metabolic chambers and exposed to 1 day of energy balance, 2 days of fasting, and 2 days of ad-libitum refeeding.

Interventions

Fasting-refeeding cycle

Participants will be maintained in metabolic chambers and exposed to 1 day of energy balance with a standard diet, 2 days of fasting (only water), and 2 days of ad-libitum refeeding using a liquid diet provided in hydration bladders to avoid portion control.

Primary outcome measure

  • Compensatory response [ Time Frame: The cumulative energy balance is calculated one time using the data of 5 inpatient days ]

Central Contacts and Locations

Central contacts

Rodrigo Fernandez-Verdejo, PhD

2257632594Rodrigo.Fernandez@pbrc.edu

Eric Ravussin, PhD

2257633186Eric.Ravussin@pbrc.edu

Locations

Pennington Biomedical Research Center

Recruiting

Baton Rouge, Louisiana, United States, 70808

Contacts

Rodrigo Fernández-Verdejo, PhD

225-763-2594rodrigo.fernandez@pbrc.edu

More Information

Sponsor

Pennington Biomedical Research Center

Last update posted

May 29, 2026

Last verified

May, 2026

Keywords

  • Energy expenditure
  • Energy intake
  • Energy balance
  • Set point model
  • Dual-intervention point model

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-03. This information was provided to ClinicalTrials.gov by Pennington Biomedical Research Center on 2026-05-29.