A parallel, single-blinded, multi-centre randomized controlled trial conducted at the South Australian Health and Medical Research Institute (SAHMRI) and the Mary Mackillop Institute for Health Research (MMIHR; Australian Catholic University), by researchers from the University of Adelaide, Australian Catholic University and La Trobe University.

In a parallel groups design, a total of 268 individuals will be recruited across both sites. After a 2-week baseline period, and a baseline metabolic visit, participants will be randomized into one of two groups (TRE, time-restricted eating; CP, current practice guidelines). All participants will receive five (5) telehealth consultations at baseline, week 2, 4, 8 and 12, the content of which will be based around their randomized condition. They will undergo metabolic testing on two (2) further occasions (4 months, 12 months) over a 12-month period to assess the changes in primary and secondary outcomes.

Inclusion Criteria:

• Study participants will be aged 35 to 70 years, overweight or obese (BMI: >25 but <45 kg/m2), ≥15 on the AUSDRISK assessment tool and have HbA1c <6.5% at screening

Exclusion Criteria:

Type 1 or type 2 diabetes, or diabetes detected at screening HbA1c ≥6.5% (48 mmol/mol).

• A personal history/diagnosis (self-reported) of:

  • 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
  • currently receiving, or have received treatment/diagnosis of cancer in the past 3 years (excluding non-melanoma skin cancer)
  • significant liver or kidney disease
  • 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

and/or any other condition deemed unstable by the study physician.

Currently taking the following medications:

• any medication used, or known to lower blood glucose, or antidiabetic medications, including, but not limited to: SGLT2 inhibitors, metformin, sulfonylureas, glucagon-like peptide-1 (GLP-1) analogues [i.e. exenatide], thiazolidinediones or DPP-IV inhibitors [i.e. 'gliptins'])
• Medications affecting weight, appetite or gut motility, including, but not limited to: (domperidone, cisapride, orlistat, phentermine, topiramate).
• Diuretics (i.e. frusemide, thiazides) or combination blood pressure medications containing a diuretic
• Beta-blockers
• Glucocorticoids
• Anti-epileptic medications
• Antipsychotic medications
• Opioid medications unless combined with paracetamol in a single formulation and used occasionally on a PRN basis

Additional exclusion criteria include:

• do not consume a regular breakfast (i.e. eat breakfast on an average of 5 or more days per week), and do not eat for more than 12 hours per day on an average of 5 or more days per week
• have an extreme or restricted pattern of eating (i.e. following an intermittent fasting diet) or are already engaged in a TRE protocol
• shift-workers
• pregnant, planning a pregnancy or currently breastfeeding
• those who have lost or gained >5% of body weight in the last 6 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)
• Participants will not have seen a dietitian in the preceding 3 months.
• score on K10 ≥30 (Kessler Psychological Distress scale)
• score on EDEQ ≥2.8 (Eating Disorder Examination Questionnaire)

The data that support the findings of this study will be available from the corresponding author for a period of 36 months from publication, upon reasonable request for academic use. The data will not be made publically available, as it contains information that could compromise research participant consent.

36 months from date of publication

Reasonable requests of data for academic use will be considered. Requests can be made to the corresponding author of the publication. Data will not be made publically available as it contains information that could compromise research participant consent.