An interventional study of Fasting-refeeding cycle in Obesity and Underweight, sponsored by Pennington Biomedical Research Center. Recruiting at 1 site in United States. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-29.
Sponsored by Pennington Biomedical Research Center · Not applicable, Interventional, and Basic science
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.
Background:
Although body weight regulation models have been proposed, experimental approaches for testing their predictions are lacking. The set point (SP) model proposes that a biologically determined fatness is defended by activating compensatory responses to prevent its change. The dual-intervention point (DIP) model proposes that there are two levels of fatness (lower and upper intervention points) within which fatness is weakly regulated. Compensatory responses would only be activated once the lower or upper intervention points are reached. In response to prolonged fasting, the SP model predicts the compensatory responses to be independent of the initial body weight. In contrast, the DIP model predicts higher responses in individuals who are closer to the lower intervention point (low body weight) compared to those who are farther away (obesity). None of these models predicts a different response in men vs. women. Our pilot and feasibility study will implement an experimental approach to test these predictions in humans by thoroughly measuring compensatory responses in energy expenditure and energy intake.
Design:
Twelve individuals (3 men with low body weight and 3 with obesity; 3 women with low body weight and 3 with obesity) will be kept inpatient in metabolic chambers for 5 consecutive days and exposed to a 1-day energy balance, 2-day fasting, and 2-day ad-libitum refeeding. The primary outcome will be the extent of compensatory response, calculated as the cumulative energy balance during the 5-day inpatient period.
Objectives:
Relevance:
Understanding how body weight is regulated in humans can help to prevent or treat obesity. In this pilot and feasibility study, the investigators propose an experimental approach to test the predictions of two body weight regulation models in response to fasting and explore potential sex differences. These preliminary data will be used to design and power future studies for testing models of body weight regulation in humans.
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 12 is below the median of 67 across 9,006 interventional studies indexed under Obesity.
Browse Obesity studies →Pennington Biomedical Research Center is the lead sponsor of 284 studies on the registry; 31 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
The human immunodeficiency virus, which weakens the immune system.
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Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
Behavioral: 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.
Compensatory response
Cumulative energy balance during the fasting-refeeding cycle
Time frame: The cumulative energy balance is calculated one time using the data of 5 inpatient days
Timing of the compensatory response
Cumulative energy balance during different time periods of the 5-day fasting-refeeding cycle
Time frame: The cumulative energy balance calculated for the following time periods along the 5-day fasting-refeeding cycle: day 1 to 2, day 1 to 3, day 1 to 4, during fasting (day 2 to 3), and during refeeding (day 4 to 5)
Protein balance
Protein balance (intake minus oxidation) during the fasting-refeeding cycle
Time frame: Protein balance is calculated one time using the data of 5 inpatient days
Carbohydrate balance
Carbohydrate balance (intake minus oxidation) during the fasting-refeeding cycle
Time frame: Carbohydrate balance is calculated one time using the data of 5 inpatient days
Lipid balance
Lipid balance (intake minus oxidation) during the fasting-refeeding cycle
Time frame: Lipid balance is calculated one time using the data of 5 inpatient days
Overall appetite
Calculated from the results of visual analog scales that record hunger, satiety, fullness, and prospective food consumption
Time frame: Overall appetite is measured 8 times per day (every 2 hours from approximately 8:00 AM) during the 5 inpatient days
Food preference
Measured using the Food Preference Questionnaire
Time frame: Measured once a day, in the fasting state (at approximately 8:00 AM), during the 5 inpatient days
Physical activity
Measured with wrist-worn accelerometers
Time frame: Measured continuously (i.e. for 24 hours) every day during the 5 inpatient days
Sleeping metabolic rate
Measured within the metabolic chamber, between 2:00 and 5:00 AM, and extrapolated to 24 hours
Time frame: Measured every day during the 5 inpatient days
Leptin
Circulating concentrations of leptin
Time frame: Measured once a day, in the fasting state (at approximately 8:00 AM), during the 5 inpatient days
Appetite-regulating hormones
Circulating concentrations of ghrelin and insulin
Time frame: Measured once a day, in the fasting state (at approximately 8:00 AM), during the 5 inpatient days
Metabolites
Circulating concentrations of glucose, fatty acids, ketone bodies
Time frame: Measured once a day, in the fasting state (at approximately 8:00 AM), during the 5 inpatient days
Thyroid axis
Circulating concentrations of T4
Time frame: Measured once a day, in the fasting state (at approximately 8:00 AM), during the 5 inpatient days
Plan to share: Yes — The de-identified data collected will be shared upon appropriate request as part of the NORC repository of Pennington Biomedical Research Center
Supporting information: Study protocol, Informed consent form
Time frame: After publication of the results for the main outcome
Access criteria: Upon appropriate request
Data sharing details ↗ · my.pbrc.edu
No publications or documents are linked to this record.
Started Jan 2025 (actual). Primary completion is estimated for Oct 2026, 20 months after the start.
Of 3,680 non-industry interventional studies with no phase under Obesity, half reached primary completion within 23 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 43. This study's planned 20 months is below that.
Counting every sponsor, half of 3,843 studies reached it within 22 months; a quarter within 10 and three quarters within 42.
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