An interventional study of Fasting in Fasting, sponsored by Cornell University. Completed at 1 site in United States. Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-09-10.
Sponsored by Cornell University · Not applicable, Interventional, and Basic science
During fasting, the body shifts from using carbohydrates to relying more on fat as its main source of energy. This process is known as the 'metabolic shift'. Fat tissue helps supply this energy by breaking down stored fat into fatty acids, which are released into the bloodstream and transported to organs throughout the body. In addition to fatty acids, many other substances in the blood (such as metabolites) change during fasting to help maintain normal body function.
Immune cells also circulate in the blood and play an important role in protecting the body against infections and diseases such as cancer. However, it is not yet well understood how the metabolic shift during fasting affects immune cell function. The purpose of this study is to investigate how 24 hours of fasting influences immune cell metabolism and function.
Rationale: Fasting leads to changes in metabolism and immune function. However, the specific biological connections between these processes are not fully understood. By studying how fasting affects immune cells, this study aims to clarify the bidirectional relationship between metabolism and immune function.
Objectives: The primary objective is to investigate the impact of fasting on immune cells known as peripheral blood mononuclear cells (PBMCs) in healthy adults. The study will examine four main features of these cells:
The secondary objectives are to 1) study how fasting affects PBMC gene expression (whole genome single cell transcriptome) and blood metabolites, 2) identify relationships between changes in metabolites and changes in immune cell function and gene expression, and 3) investigate how fasting-induced changes in gene expression are affected by refeeding. In addition, the explorative objectives are to determine how fasting affects the immune cell population residing in subcutaneous adipose.
Study design: The Meta-SHIFT study is a single-arm intervention study that investigates the effect of fasting by comparing the same subjects 2 hours after meal consumption (fed state or 'baseline') and 24 hours after baseline (fasted state or '24 hours'). Participants will serve as their own control.
Study Population: The study will include twenty-eight healthy adults between 18 and 40 years old, who have a body mass index (BMI) between 18.5-24.9 kg/m2 and no chronic diseases.
Intervention: The evening before the fasting intervention, research participants will consume a standardized dinner (ad libitum). The next morning, two hours before baseline, participants will receive a standardized breakfast shake (energy adjusted for BMR), followed by a fasting period of 26 hours. During the fasting period, research participants are not allowed to eat or drink anything except for water and sugar-free tea provided by the investigators, which may be consumed ad libitum. Two hours after the consumption of the standardized shake, the participants are considered to be in the 'fed state', which is defined as baseline. At baseline, the first blood samples (and optional adipose tissue biopsy) will be taken. At 24 hours after baseline, the participants are considered to be in the 'fasted state', and the second set of blood samples (and optional adipose tissue biopsy) will be taken. A period of 24 hours between sampling points is chosen to prevent the effects of circadian rhythm on the outcome measures. Additionally, the effects of re-introducing food after fasting will be examined (refed state). The refed state is defined as 2 hours after consumption of the second standardized breakfast shake that ends the fasted state, which is 26 hours after baseline. At 26-hours, the third set of blood samples will be collected.
392 studies on the registry are indexed under Fasting; 63 are open to participants now.
This study's enrollment of 28 is below the median of 45 across 311 interventional studies indexed under Fasting.
Browse Fasting studies →Cornell University is the lead sponsor of 103 studies on the registry; 16 are open to participants now.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
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.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
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.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Platelets
Blood cells that help blood clot. Too few raises the risk of bleeding and bruising. A usual adult range is about 150–400 × 10⁹/L (150,000–400,000 per µL); each lab has its own reference range.
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.
26-hour fasting
Other: Fasting
After consumption of a standardized breakfast (energy content adjusted to individual BMR), participants will undergo a 26-hour fast (water only), followed by consumption of a second standardized breakfast.
Change in PBMC energy metabolism.
Change from baseline PBMC glucose dependence (%) and mitochondrial dependence (%) at 24-hours, as measured by the flow cytometry-based CENCAT method.
Time frame: Baseline, 24 hours
Change in activated PBMC energy metabolism.
Change from baseline activated PBMC glucose dependence (%) and mitochondrial dependence (%) at 24-hours, as measured by the flow cytometry-based CENCAT method. PBMCs are activated in vitro for 2-hours using LPS or TransAct.
Time frame: Baseline, 24 hours
Change in inflammatory capacity of activated PBMCs.
Change from baseline activated PBMC cytokine positive cells (%) and relative cellular cytokine quantity (fluorescent intensity) at 24-hours, as measured by a flow cytometry-based intracellular cytokine stain. PBMCs are activated in vitro for 2-hours using LPS or TransAct.
Time frame: Baseline, 24 hours
Change in PBMC subset abundance.
Change from baseline PBMC subset counts, as assessed with a hematology analyzer.
Time frame: Baseline, 24 hours
Change in PBMC transcriptome.
Change from baseline whole genome single cell RNA expression in PBMCs at 24 hours.
Time frame: Baseline, 24 hours
Change in plasma metabolite profile.
Change from baseline plasma metabolite levels at 24 hours.
Time frame: Baseline, 24 hours
Change in PBMC RNA expression.
Change from baseline and 24-hour RNA expression of identified fasting target genes in PBMCs at 26 hours.
Time frame: Baseline, 24 hours, 26 hours
Change in subcutaneous adipose tissue immune cell transcriptome.
Change from baseline whole genome single cell RNA expression in subcutaneous adipose tissue immune cells at 24 hours.
Time frame: Baseline, 24 hours
This study is completed, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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