ObesityNCT03354169
Daytime vs. Delayed Eating Among Obese Individuals
A study testing Eating Condition in people with Obesity, run by University of Pennsylvania at 1 site in United States.
Trial summary
The randomized, cross-over design study is designed to determine how timing of eating affects weight, adiposity, energy metabolism, and gene expression. Obese participants will be provided isocaloric meals and snacks to be consumed in one of two prescribed eating conditions -- daytime eating and delayed eating. Read more about this study
- Who is it for?
- Ages 21 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity
- What is being tested?
- Eating Condition
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 38 participants
- Where
- 1 siteUnited States
- Study dates
- 7 Feb 2018to 2 Mar 2023
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 21 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- age 21-50
- BMI of 30-50 kg/m2
- stable weight (±10 lb) over the previous 6 months
- women must be pre-menopausal with regular menstrual cycles
Who cannot join
- unstable, serious medical conditions
- use of medicine linked to weight gain/loss
- cardiac conditions
- cancer
- diabetes
- autoimmune disease
Show all 16Show fewer
- use of illicit drugs, melatonin, diuretics or hypnotics
- involved in a current weight loss program
- presence of an untreated sleep disorder (determined by surveys and actigraphy)
- those who work shift work
- those with extreme chronotypes
- habitual waking outside of 0600h-0930h
- habitual bedtime <2200h or >2400h
- sleep duration of <6.5 or >8.5 h/night.
- psychiatric exclusions will be: depression (Patient Health Questionnaire-9 score ≥9), lifetime bipolar disorder, psychosis, or eating disorder; or any other severe psychiatric disorder judged to interfere with study adherence as assessed by the MINI International Neuropsychiatric Interview.
- structured exercise >3 d/wk, for >30 min measured by exercise logs and actigraphy; normal activity levels are required during the study (±30 min/wk of baseline level).
Trial locations and contacts
1 site in 1 country.
United States1 site
Center for Weight and Eating Disorders, Perelman School of Medicine, University of Pennsylvania
Philadelphia, Pennsylvania, 19104
About this study
Official title: Randomized Controlled Trial Examining the Effects of Meal Timing Among Obese Individuals
The randomized, cross-over design study is designed to determine how timing of eating affects weight, adiposity, energy metabolism, and gene expression. Obese participants will be provided isocaloric meals and snacks to be consumed in one of two prescribed eating conditions -- daytime eating and delayed eating.
Read the detailed description
The study consists of the following phases - screening, assessment visit 1, eating condition 1, assessment visit 2, a wash-out period, assessment visit 3, eating condition 2 and assessment visit 4, as discussed in detail below. The assessment visits will all consist of the same procedures and will take place at the Center for Human Phenomic Science (CHPS) of the Hospital of the University of Pennsylvania before and after each of the eating conditions (four times total). The four 28-hour inpatient assessments will consist of blood draws, adipose (fat) tissue sampling, a dual energy X-ray absorptiometry (DEXA) scan, and a resting metabolic rate test.
During the screening period in order to determine eligibility, participants must complete a 2-part screening visit; This includes:
- A complete physical examination
- Tests of blood to screen for any conditions such as diabetes or any serious, uncontrolled medical condition that may interfere with participation in the study.
- An Electrocardiogram (EKG) test
- Urine Pregnancy Test
- Urine Drug Screening
- the completion of several self-report questionnaires and structured interviews
During the screening period, participants will also be asked to keep a 10-day food log where they will record all food and beverages consumed and their sleep and exercise schedule. Participants will be asked to wear an Actigraph wrist watch at this time.
Following successful completion of the screening period, participants will complete the first of 4 assessment visits. All assessment visits will follow the same protocol.
Assessment Visit Day 1 Procedures:
The visit will include 28 hours (overnight) spent at the CHPS, where meals and snacks will be provided. At each of the assessment visits participants will be given a urine drug screening and, if appropriate, a pregnancy test. The lights will be dim in the hospital room to control for light.
Participants will arrive at 7:00 am. Starting at 8:00 am, blood will be drawn every four hours. From this blood gene expression and hormones related to metabolism, eating, and sleep will be measured.
Following the first blood draw, resting metabolic rate is measured for 45 minutes. Lunch is then provided, followed by a measurement of body composition using a DEXA scan. Next, the adipose tissue sampling procedure will begin. Lastly, the participants will complete a series of cognitive tests administered on a laptop.
Participants will be provided meals and snacks during their visit and are free to watch television or participate in other sedentary pastimes while they are there.
Assessment Visit Day 2 Procedures:
After an overnight fast, participants will undergo the Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT) on the morning of day 2.
Following the FSIGT test, participants will be served a meal and during the first assessment visit, participants will be randomly assigned to start with one of two eating conditions for the next 8 weeks: 1) Daytime or 2) Delayed. Following randomization, participants will be discharged from CHPS and begin eating condition 1.
If participants are assigned to the daytime eating condition first, they will be asked to consume all of their meals and snacks each day between 8:00 am and 7:00 pm. If they are assigned to the delayed eating condition first, they will be asked to consume all of their meals and snacks between 12 noon and 11:00 pm each day. Participants will eat on this schedule for 8 weeks. During the two, 8-week eating periods, all of the meals and snacks will be provided by the research kitchen. During the eating conditions, participants will be asked to complete daily self-report queries concerning their adherence to the food, sleep, and physical activity requirements of the study.
Following eating condition 1, participants will return for assessment visit 2. This assessment visit follows the same procedures as all other assessment visits. Following assessment visit 2, participants will begin their 2 week washout period where they are instructed to eat as they normally would whenever they like. Following the two-week washout period, participants will return for assessment visit 3, after which they will begin eating condition 2. Following 8 weeks of eating condition 2 participants will return for their final visit, assessment visit 4. After this final assessment, participation in the study will be complete.
- Conditions
- Obesity
- Being tested
- Eating Condition, No Intervention; withdrawn before randomization
- Keywords
- Metabolism, Eating, Circadian Rhythms
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Eating ConditionBehavioural
Participants will be randomly assigned to eat per the prescribed eating condition for 8 weeks during eating condition 1. They will complete the alternate eating condition for 8 weeks during eating condition 2.
No Intervention; withdrawn before randomizationOther
These participants were withdrawn and did not receive an intervention.
| Study group | Role | What they receive |
|---|---|---|
| Daytime Eating Condition | Experimental | Participants will be asked to eat all of their meals and snacks, as provided by the study, between 0800 and 1900. Receives: Behavioral: Eating Condition |
| Delayed Eating Condition | Experimental | Participants will be asked to eat all of their meals and snacks, as provided by the study, between 1200 and 2300. Receives: Behavioral: Eating Condition |
| Withdrawn before randomization | Other | Two participants completed the screening process and started the first inpatient assessment visit but were withdrawn prior to completion of the assessment visit and were not randomized to start the intervention. They were not included in data analysis. Receives: Other: No Intervention; withdrawn before randomization |
What is being measured
The primary outcome is the main question the study is designed to answer.
Body Mass (Weight)
changes in body mass, as measured by a calibrated digital scale, will be explored.
Measured: pre-post changes between the daytime and delayed eating conditions (each 8 weeks long)
Adiposity - Total Body Fat
changes in measures of total body fat, as measured by a DEXA scan, will be explored.
Measured: pre-post changes between the daytime and delayed eating conditions (8 weeks).
Energy Homeostasis Outcomes - REE
Changes in resting energy expenditure values will be explored.
Measured: pre-post changes between the daytime and delayed eating conditions (8 weeks).
Energy Homeostasis - Respiratory Quotient
Respiratory quotient (RQ) was measured with a Parvo-Medics metabolic cart. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body, when the body is in a steady state.
Measured: pre-post changes between the daytime and delayed eating conditions (8 weeks).
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted27 Nov 2017
- Study start7 Feb 2018
- Primary completion2 Mar 2023
- Study completion2 Mar 2023
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Other trials for ObesityStudies of the same condition, open and under way.
- More trials run by University of PennsylvaniaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Model description
- Randomized within subjects, cross-over design
- Masking
- None (open label)
- Enrolment
- 38 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Pennsylvania
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Kelly Allison, University of Pennsylvania
- Investigators
- Kelly Allison, PhD, Principal investigator, University of Pennsylvania
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03354169
- Sponsor's protocol ID
- 828317
- Other IDs
- R01DK117488
- Status last verified
- Nov 2025
- First submitted
- 21 Nov 2017
- Last updated
- 21 Nov 2025
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 21 Nov 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Randomized Controlled Trial Examining the Effects of Meal Timing Among Obese Individuals
- ClinicalTrials.gov ID
- NCT03354169
- Acronym / sponsor ID
- 828317
- Conditions
- Obesity
- Keywords
- Metabolism, Eating, Circadian Rhythms
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 38 participants (actual)
- Lead sponsor
- University of PennsylvaniaUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 7 Feb 2018 (actual)
- Primary completion
- 2 Mar 2023 (actual)
- Study completion
- 2 Mar 2023 (actual)
- First posted
- 27 Nov 2017 (actual)
- Results
- Posted 21 Nov 2025
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The randomized, cross-over design study is designed to determine how timing of eating affects weight, adiposity, energy metabolism, and gene expression. Obese participants will be provided isocaloric meals and snacks to be consumed in one of two prescribed eating conditions -- daytime eating and delayed eating.
Detailed description
The study consists of the following phases - screening, assessment visit 1, eating condition 1, assessment visit 2, a wash-out period, assessment visit 3, eating condition 2 and assessment visit 4, as discussed in detail below. The assessment visits will all consist of the same procedures and will take place at the Center for Human Phenomic Science (CHPS) of the Hospital of the University of Pennsylvania before and after each of the eating conditions (four times total). The four 28-hour inpatient assessments will consist of blood draws, adipose (fat) tissue sampling, a dual energy X-ray absorptiometry (DEXA) scan, and a resting metabolic rate test.
During the screening period in order to determine eligibility, participants must complete a 2-part screening visit; This includes:
- A complete physical examination
- Tests of blood to screen for any conditions such as diabetes or any serious, uncontrolled medical condition that may interfere with participation in the study.
- An Electrocardiogram (EKG) test
- Urine Pregnancy Test
- Urine Drug Screening
- the completion of several self-report questionnaires and structured interviews
During the screening period, participants will also be asked to keep a 10-day food log where they will record all food and beverages consumed and their sleep and exercise schedule. Participants will be asked to wear an Actigraph wrist watch at this time.
Following successful completion of the screening period, participants will complete the first of 4 assessment visits. All assessment visits will follow the same protocol.
Assessment Visit Day 1 Procedures:
The visit will include 28 hours (overnight) spent at the CHPS, where meals and snacks will be provided. At each of the assessment visits participants will be given a urine drug screening and, if appropriate, a pregnancy test. The lights will be dim in the hospital room to control for light.
Participants will arrive at 7:00 am. Starting at 8:00 am, blood will be drawn every four hours. From this blood gene expression and hormones related to metabolism, eating, and sleep will be measured.
Following the first blood draw, resting metabolic rate is measured for 45 minutes. Lunch is then provided, followed by a measurement of body composition using a DEXA scan. Next, the adipose tissue sampling procedure will begin. Lastly, the participants will complete a series of cognitive tests administered on a laptop.
Participants will be provided meals and snacks during their visit and are free to watch television or participate in other sedentary pastimes while they are there.
Assessment Visit Day 2 Procedures:
After an overnight fast, participants will undergo the Frequently Sampled Intravenous Glucose Tolerance Test (FSIGT) on the morning of day 2.
Following the FSIGT test, participants will be served a meal and during the first assessment visit, participants will be randomly assigned to start with one of two eating conditions for the next 8 weeks: 1) Daytime or 2) Delayed. Following randomization, participants will be discharged from CHPS and begin eating condition 1.
If participants are assigned to the daytime eating condition first, they will be asked to consume all of their meals and snacks each day between 8:00 am and 7:00 pm. If they are assigned to the delayed eating condition first, they will be asked to consume all of their meals and snacks between 12 noon and 11:00 pm each day. Participants will eat on this schedule for 8 weeks. During the two, 8-week eating periods, all of the meals and snacks will be provided by the research kitchen. During the eating conditions, participants will be asked to complete daily self-report queries concerning their adherence to the food, sleep, and physical activity requirements of the study.
Following eating condition 1, participants will return for assessment visit 2. This assessment visit follows the same procedures as all other assessment visits. Following assessment visit 2, participants will begin their 2 week washout period where they are instructed to eat as they normally would whenever they like. Following the two-week washout period, participants will return for assessment visit 3, after which they will begin eating condition 2. Following 8 weeks of eating condition 2 participants will return for their final visit, assessment visit 4. After this final assessment, participation in the study will be complete.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- Randomized within subjects, cross-over design
| Arm | Type | Receives |
|---|---|---|
| Daytime Eating Condition | Experimental | Behavioral: Eating ConditionParticipants will be asked to eat all of their meals and snacks, as provided by the study, between 0800 and 1900. |
| Delayed Eating Condition | Experimental | Behavioral: Eating ConditionParticipants will be asked to eat all of their meals and snacks, as provided by the study, between 1200 and 2300. |
| Withdrawn before randomization | Other | Other: No Intervention; withdrawn before randomizationTwo participants completed the screening process and started the first inpatient assessment visit but were withdrawn prior to completion of the assessment visit and were not randomized to start the intervention. They were not included in data analysis. |
Who may qualify
- Ages
- 21 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- age 21-50
- BMI of 30-50 kg/m2
- stable weight (±10 lb) over the previous 6 months
- women must be pre-menopausal with regular menstrual cycles
Key exclusion criteria (16 listed)
- unstable, serious medical conditions
- use of medicine linked to weight gain/loss
- cardiac conditions
- cancer
- diabetes
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Eating ConditionParticipants will be randomly assigned to eat per the prescribed eating condition for 8 weeks during eating condition 1. They will complete the alternate eating condition for 8 weeks during eating condition 2. | Behavioural | Daytime Eating Condition, Delayed Eating Condition |
| No Intervention; withdrawn before randomizationThese participants were withdrawn and did not receive an intervention. | Other | Withdrawn before randomization |
Primary outcome
Body Mass (Weight)
Time frame: pre-post changes between the daytime and delayed eating conditions (each 8 weeks long)
changes in body mass, as measured by a calibrated digital scale, will be explored.
Adiposity - Total Body Fat
Time frame: pre-post changes between the daytime and delayed eating conditions (8 weeks).
changes in measures of total body fat, as measured by a DEXA scan, will be explored.
Energy Homeostasis Outcomes - REE
Time frame: pre-post changes between the daytime and delayed eating conditions (8 weeks).
Changes in resting energy expenditure values will be explored.
Energy Homeostasis - Respiratory Quotient
Time frame: pre-post changes between the daytime and delayed eating conditions (8 weeks).
Respiratory quotient (RQ) was measured with a Parvo-Medics metabolic cart. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body, when the body is in a steady state.
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 21 Nov 2025.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Kelly Allison, PhD principal investigator
University of Pennsylvania
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Eating Condition in people with Obesity, run by University of Pennsylvania at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 16 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 21 Nov 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 21 Nov 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Body Mass (Weight) (time frame: pre-post changes between the daytime and delayed eating conditions (each 8 weeks long)). The study lists 4 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 21 Nov 2025.