ObesityOMITNCT05769335
Calories or Time Restriction to Alter Biomarkers of Aging and Diabetes
A study testing eCR, dCR and CR in people with Obesity, run by University of Adelaide at 1 site in Australia.
Trial summary
Type 2 diabetes and cardiovascular disease are an increasing problem in Australia and around the world, and are partly linked to increased rates of obesity, together with sedentary lifestyles. Read more about this study
- Who is it for?
- Ages 35 to 75 years
- Conditions the study is for
- Obesity
- What is being tested?
- eCR, dCR and CR
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 114 participants
- Where
- 1 siteAustralia
- Study dates
- 15 Mar 2023to 17 Apr 2025
- Phase
- Interventional
- Are there results?
- None posted in the registry
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 35 to 75 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Overweight or obesity (BMI 25.1 - 44.9 kg/m2)
- Elevated waist circumference (race specific),
- Elevated fasting blood glucose (>5.6 mmol/L).
Who cannot join
- A personal history/diagnosis (self-reported) of:
- diabetes (type 1 or 2)
- major psychiatric disorders (schizophrenia, major depressive disorder, bipolar disorder, eating disorders)
- gastrointestinal disorders/disease (including malabsorption)
- haematological disorders (i.e. thalassemia, iron-deficiency anaemia)
- insomnia
Show all 39Show fewer
- obstructive sleep apnea
- night eating syndrome
- diagnosis or treatment of cancer in the past 3 years (excluding non-melanoma skin cancer)
- significant liver or kidney diseases that require ongoing medical care
- previous or planned gastro-intestinal surgery (including bariatric surgery)
- Congestive heart failure (NYHA stage 2 or above)
- Previous myocardial infarction or significant cardiac event ≤ 6 months prior to screening
- Previous cerebrovascular event ≤ 12 months prior to screening
- Any autoimmune disease (i.e. rheumatoid arthritis)
- Coeliac disease
- Score less than 12 of the Australian Diabetes (AUSD) risk assessment tool
- Do not eat for a 12 hour window each day for 5 or more days per week
- Have extreme or restricted patterns of eating (i.e. following an intermittent fasting diet) or already engage in CR
- Other dietary restrictions including vegans, gluten or nut allergies
- Night shift-workers (>3 shifts per month)
- pregnant, planning a pregnancy or currently breastfeeding
- those who have lost or gained >5% of body weight in the last 6 months
- donated blood in past 3 months
- current smokers of cigarettes/marijuana/e-cigarettes/vaporisers
- anyone unable to comprehend the study protocol or provide informed consent (i.e. due to English language or cognitive difficulties)
- do not own, or are not comfortable using, a smart phone and applications
- Currently taking the following medications:
- Anti-diabetic medications that lower blood glucose including, but not limited to: SGLT2 inhibitors, metformin, sulfonylureas, glucagon-like peptide-1 (GLP-1) analogues [i.e. semaglutide], thiazolidinediones
- affecting weight, appetite or gut motility, including, but not limited to semaglutide, domperidone, cisapride, orlistat, phentermine, topiramate.
- Diuretics (i.e. frusemide, thiazides) or combination blood pressure medications containing a diuretic
- Beta-blockers
- Glucocorticoids
- Anti-epileptic medications (i.e. pregabalin and gabapentin)
- Tricyclic antidepressants
- Some serotonin and norepinephrine reuptake inhibitors (i.e. vortioxetine, mirtazapine and venlafaxine)
- Regular use of benzodiazepines or other sleep aids, including melatonin
- Antipsychotic medications
- Opioid medications unless combined with paracetamol in a single formulation and used occasionally on as needs basis
Trial locations and contacts
1 site in 1 country.
Australia1 site
South Australian Health and Medical Research Institute / The University of Adelaide
Adelaide, South Australia, 5000
About this study
Official title: The Effects of Caloric Restriction Plus Time Restriction on Glycemia, Circadian Rhythms and Cardiometabolic Health
Type 2 diabetes and cardiovascular disease are an increasing problem in Australia and around the world, and are partly linked to increased rates of obesity, together with sedentary lifestyles. This study will compare caloric restriction (CR) diets that restrict the amount of food that is eaten with CR diets that also restrict the time that the food is eaten, to either early or late in the day, on risk factors for type 2 diabetes and cardiovascular diseases over 2 months.
Read the detailed description
In a parallel groups design, a total of 114 individuals will be recruited. After a two-week lead in and collection of data from activity monitors and continuous glucose monitors, plus a 28 hour (h) metabolic ward in-patient stay, participants will be randomised into one of three groups (eCR, 8-hour early time restriction + calorie restriction (e.g. 8:00-16:00); dCR, 8-hour delayed time restriction + calorie restriction (e.g. 12:00-20:00); CR, caloric restriction (>12 hour eating window (e.g. 8:00-20:00). All participants will receive individualised menus and foods that will be delivered to their homes by a supermarket delivery service at energy balance for 1 week (baseline) and at 70% of energy balance for a further 8 weeks. Repeat assessment occurs from 6-8 weeks with the final metabolic ward stay at 8-weeks to assess changes in primary and secondary outcomes.
There are three preplanned sub-studies from the parent trial:
- OMIT-Immune sub-study All participants will have blood samples collected at six timepoints over 24 hours and stool samples will be collected at two timepoints in a subset. The aims of this sub-study are to 1) characterize the changes in 24 h rhythm (mesor, amplitude and acrophase) of immune cells by flow cytometry over 24 hours, 2) describe the changes in the diversity of bacterial in response to intervention and 3) compare the effects of 8 weeks of CR versus eCR and dCR on immune profiles and gut microbiome.
- OMIT-BP sub-study All participants will have blood and urine samples collected at six timepoints over 24 hours. A subset of participants will wear 24 h ambulatory blood pressure monitors. The aims of this sub-study are to compare the effects of CR versus eCR and dCR on 1) the 24-hour profile of blood pressure assessed by ambulatory blood pressure monitoring, 2) Plasma markers of blood pressure regulation and 3) markers of renal function. We hypothesise that both eCR and dCR will alter and enhance these parameters and markers in comparison to CR. Changes in the circadian mesor, amplitude and acrophase in: systolic blood pressure, diastolic blood pressure, heart rate, pulse pressure, mean arterial pressure, nocturnal blood pressure dipping, morning blood pressure surge, plasma renin, aldosterone, creatinine, Urinary potassium, sodium, cortisol, creatinine.
- OMIT- Six month follow up. All participants will be instructed to continue their respective diet intervention and return to the clinic after an additional 16 weeks for a fasting blood sample and assessment of body composition. The aims of this sub-study are to 1) compare the 6 months effects of CR versus eCR and dCR on body composition and fasting blood samples metabolic health from baseline; 2) explore the factors that drive the intention-behaviour gap (describing the failure to translate intentions into action) relation to diet adherence. We hypothesize that participants will maintain the intervention-induced improvements in behavioural and metabolic health outcomes. Additionally, changes in body weight, waist and hip circumference, lean mass, fat mass, blood pressure, glycated hemoglobin, fasting plasma glucose, insulin, total cholesterol, LDL, HDL, triglycerides are assessed.
- Conditions
- Obesity
- Being tested
- eCR, dCR, CR
- Keywords
- Dietary intervention, Inflammation, Circadian rhythms, Cardiometabolic health
- Medical subject headings
- Obesity, Inflammation
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
eCROther
Eating time window from 8:00 to 16:00
dCROther
Eating time window from 12:00 to 20:00
CROther
Eating time window from 8:00 to 20:00
| Study group | Role | What they receive |
|---|---|---|
| early calorie restriction (eCR) | Experimental | Individuals will be provided with menus prescribed at 70% of calculated energy requirements and instructed to eat within 8 h/day (e.g. 8:00 - 16:00) every day for 8 weeks, except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. Receives: Other: eCR |
| delayed calorie restriction (dCR) | Experimental | Individuals will be provided with menus prescribed at 70% of calculated energy requirements and instructed to eat within 8 h/day (e.g 12:00 - 20:00) every day for 8 weeks, except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. Receives: Other: dCR |
| Calorie restriction (CR) | Active comparator | Individuals will be provided with menus prescribed at 70% of calculated energy requirements every day for 8 weeks. The menus will encourage breakfast and after-dinner consumption of the snack to eat over at least a 12 hour time frame per day (e.g. 8:00 - 20:00), except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. Receives: Other: CR |
What is being measured
The primary outcome is the main question the study is designed to answer.
Glucose area under curve (AUC) after 3 meals
Change in glucose AUC after 3 meals
Measured: 8 weeks
Secondary outcomes (4)
Insulin area under the curve (AUC)
Change in insulin AUC (sum of 3 meals)
Measured: 8 weeks
Fasting insulin
Change in fasting insulin
Measured: 8 weeks
Fasting glucose
Change in fasting glucose
Measured: 8 weeks
Change in glycated hemoglobin (HbA1c)
Change in glycated hemoglobin
Measured: 8 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Mar 2023
- Study start15 Mar 2023
- Primary completion10 Dec 2024
- Study completion17 Apr 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- The OMIT study will be a parallel, single-blinded, 3-arm randomised controlled trial.
- Masking
- None (open label)
- Enrolment
- 114 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Adelaide
- Sponsor type
- University, hospital or other
- Collaborators
- University of Sydney, Salk Institute for Biological Studies
- Responsible party
- Principal investigator, A/Prof Leonie Heilbronn, University of Adelaide
- Investigators
- Leonie Heilbronn, PhD., Principal investigator, The University of Adelaide
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05769335
- Sponsor's protocol ID
- H-2022-199
- Acronym
- OMIT
- Status last verified
- May 2025
- First submitted
- 1 Mar 2023
- Last updated
- 9 May 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 9 May 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Effects of Caloric Restriction Plus Time Restriction on Glycemia, Circadian Rhythms and Cardiometabolic Health
- ClinicalTrials.gov ID
- NCT05769335
- Acronym / sponsor ID
- OMIT / H-2022-199
- Conditions
- Obesity
- Keywords
- Dietary intervention, Inflammation, Circadian rhythms, Cardiometabolic health
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 114 participants (actual)
- Lead sponsor
- University of AdelaideUniversity, hospital or other
- Collaborators
- University of Sydney, Salk Institute for Biological Studies
- Study start
- 15 Mar 2023 (actual)
- Primary completion
- 10 Dec 2024 (actual)
- Study completion
- 17 Apr 2025 (actual)
- First posted
- 15 Mar 2023 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Type 2 diabetes and cardiovascular disease are an increasing problem in Australia and around the world, and are partly linked to increased rates of obesity, together with sedentary lifestyles. This study will compare caloric restriction (CR) diets that restrict the amount of food that is eaten with CR diets that also restrict the time that the food is eaten, to either early or late in the day, on risk factors for type 2 diabetes and cardiovascular diseases over 2 months.
Detailed description
In a parallel groups design, a total of 114 individuals will be recruited. After a two-week lead in and collection of data from activity monitors and continuous glucose monitors, plus a 28 hour (h) metabolic ward in-patient stay, participants will be randomised into one of three groups (eCR, 8-hour early time restriction + calorie restriction (e.g. 8:00-16:00); dCR, 8-hour delayed time restriction + calorie restriction (e.g. 12:00-20:00); CR, caloric restriction (>12 hour eating window (e.g. 8:00-20:00). All participants will receive individualised menus and foods that will be delivered to their homes by a supermarket delivery service at energy balance for 1 week (baseline) and at 70% of energy balance for a further 8 weeks. Repeat assessment occurs from 6-8 weeks with the final metabolic ward stay at 8-weeks to assess changes in primary and secondary outcomes.
There are three preplanned sub-studies from the parent trial:
- OMIT-Immune sub-study All participants will have blood samples collected at six timepoints over 24 hours and stool samples will be collected at two timepoints in a subset. The aims of this sub-study are to 1) characterize the changes in 24 h rhythm (mesor, amplitude and acrophase) of immune cells by flow cytometry over 24 hours, 2) describe the changes in the diversity of bacterial in response to intervention and 3) compare the effects of 8 weeks of CR versus eCR and dCR on immune profiles and gut microbiome.
- OMIT-BP sub-study All participants will have blood and urine samples collected at six timepoints over 24 hours. A subset of participants will wear 24 h ambulatory blood pressure monitors. The aims of this sub-study are to compare the effects of CR versus eCR and dCR on 1) the 24-hour profile of blood pressure assessed by ambulatory blood pressure monitoring, 2) Plasma markers of blood pressure regulation and 3) markers of renal function. We hypothesise that both eCR and dCR will alter and enhance these parameters and markers in comparison to CR. Changes in the circadian mesor, amplitude and acrophase in: systolic blood pressure, diastolic blood pressure, heart rate, pulse pressure, mean arterial pressure, nocturnal blood pressure dipping, morning blood pressure surge, plasma renin, aldosterone, creatinine, Urinary potassium, sodium, cortisol, creatinine.
- OMIT- Six month follow up. All participants will be instructed to continue their respective diet intervention and return to the clinic after an additional 16 weeks for a fasting blood sample and assessment of body composition. The aims of this sub-study are to 1) compare the 6 months effects of CR versus eCR and dCR on body composition and fasting blood samples metabolic health from baseline; 2) explore the factors that drive the intention-behaviour gap (describing the failure to translate intentions into action) relation to diet adherence. We hypothesize that participants will maintain the intervention-induced improvements in behavioural and metabolic health outcomes. Additionally, changes in body weight, waist and hip circumference, lean mass, fat mass, blood pressure, glycated hemoglobin, fasting plasma glucose, insulin, total cholesterol, LDL, HDL, triglycerides are assessed.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
- Model description
- The OMIT study will be a parallel, single-blinded, 3-arm randomised controlled trial.
| Arm | Type | Receives |
|---|---|---|
| early calorie restriction (eCR) | Experimental | Other: eCRIndividuals will be provided with menus prescribed at 70% of calculated energy requirements and instructed to eat within 8 h/day (e.g. 8:00 - 16:00) every day for 8 weeks, except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. |
| delayed calorie restriction (dCR) | Experimental | Other: dCRIndividuals will be provided with menus prescribed at 70% of calculated energy requirements and instructed to eat within 8 h/day (e.g 12:00 - 20:00) every day for 8 weeks, except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. |
| Calorie restriction (CR) | Active comparator | Other: CRIndividuals will be provided with menus prescribed at 70% of calculated energy requirements every day for 8 weeks. The menus will encourage breakfast and after-dinner consumption of the snack to eat over at least a 12 hour time frame per day (e.g. 8:00 - 20:00), except 1 evening meal per week off the program (i.e. Saturday nights) to assist with overall adherence. |
Who may qualify
- Ages
- 35 to 75 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- Overweight or obesity (BMI 25.1 - 44.9 kg/m2)
- Elevated waist circumference (race specific),
- Elevated fasting blood glucose (>5.6 mmol/L).
Key exclusion criteria (39 listed)
- diabetes (type 1 or 2)
- major psychiatric disorders (schizophrenia, major depressive disorder, bipolar disorder, eating disorders)
- gastrointestinal disorders/disease (including malabsorption)
- haematological disorders (i.e. thalassemia, iron-deficiency anaemia)
- insomnia
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 |
|---|---|---|
| eCREating time window from 8:00 to 16:00 | Other | early calorie restriction (eCR) |
| dCREating time window from 12:00 to 20:00 | Other | delayed calorie restriction (dCR) |
| CREating time window from 8:00 to 20:00 | Other | Calorie restriction (CR) |
Primary outcome
Glucose area under curve (AUC) after 3 meals
Time frame: 8 weeks
Change in glucose AUC after 3 meals
4 secondary outcomes
Insulin area under the curve (AUC)
Time frame: 8 weeks
Fasting insulin
Time frame: 8 weeks
Fasting glucose
Time frame: 8 weeks
Change in glycated hemoglobin (HbA1c)
Time frame: 8 weeks
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 9 May 2025.
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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.
Leonie Heilbronn, PhD. principal investigator
The University of Adelaide
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing eCR, dCR and CR in people with Obesity, run by University of Adelaide at 1 site in Australia.
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 3 inclusion and 39 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 9 May 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 Australia. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Glucose area under curve (AUC) after 3 meals (time frame: 8 weeks). 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 9 May 2025.