Only a matter of time (OMIT) Study - A comparison of caloric restriction versus time restriction of food intake

Brief 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. 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.

Key Inclusion Criteria

Inclusion Criteria: * Overweight or obesity (BMI 25.1 - 44.9 kg/m2) * Elevated waist circumference (race specific), * Elevated fasting blood glucose (>5.6 mmol/L). Exclusion Criteria: 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) .... Inclusion Criteria: * Overweight or obesity (BMI 25.1 - 44.9 kg/m2) * Elevated waist circumference (race specific), * Elevated fasting blood glucose (>5.6 mmol/L). Exclusion Criteria: 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 * 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 Read more

Key Exclusion Criteria

Can healthy volunteers participate?

No