The Time-Restricted Intake of Meals Study

Inclusion criteria

• Prediabetes defined by HbA1c 5.7-6.4%, or type 2 diabetes with HbA1c 6.5-6.9%
• Class I-III obesity (BMI 30-50 kg/m2)
• If on medications for hypertension, stable regimen for at least past 6 months
• Willingness to adjust timing of feeding
• Willingness and ability to eat study diet and nothing else during run-in and intervention
• Willingness to complete measurement procedures

Exclusion criteria

• Moderate to severe obstructive sleep apnea
• Shift work;
• Other sleep/circadian disorders: e.g., circadian phase delay or phase advance; restless legs syndrome, insomnia, narcolepsy, habitual sleep <6 hours/night
• Routinely ate within compressed time window in the past year (e.g., routinely eats all food within an 10-hour or narrower window, follows an intermittent fasting protocol)
• Renal dysfunction (estimated Glomerular Filtration Rate (GFR) <30 using the simplified Chronic Kidney Disease (CKD) Epidemiology Collaboration (EPI) equation 34)
• Use of glucose-lowering medications, weight loss medications, medications for sleep disorders (sedative/hypnotic drugs, stimulants), lithium, systemic corticosteroids, diuretics, blood thinners requiring regular monitoring (e.g. warfarin), anti-psychotic drugs and antiretroviral therapy
• Body weight >400 pounds (limitation of facility scales)
• >1 drink per day of alcohol
• Active substance use disorder or significant psychiatric/psychologic disorder that would interfere with participation
• Significant food allergies, preferences, intolerances, or dietary supplements that would interfere with diet adherence
• Weight loss or gain of ≥5% during past 6 months
• Pregnant, planning to become pregnant, or breastfeeding
• Planning to start a weight loss program
• Planning to leave the area prior to end of study
• Current participation in another clinical trial
• Cancer diagnosis requiring active treatment in past two years or planned treatment (with exception of localized non-melanoma skin cancer)
• Active inflammatory bowel disease, malabsorption, or history of major gastrointestinal surgery involving bowel resection
• Myocardial infarction or stroke in past 6 months
• Prior bariatric surgery
• Any serious illness that would interfere with participation
• Other conditions or situations at the discretion of the PI