Time-restricted Eating, Window Timing, Type 2 Diabetes Status and Sex on Glycemic Control

The overarching aim of this study is to evaluate the interactions between TRE window timing, type 2 diabetes status, and sex among individuals with obesity. The first objective is to compare the effects of three 9-h TRE window times (early: 7:00-16:00 h, mid: 9:30-18:30 h, delayed: 12:00-21:00 h) on real-time, free-living glycemic control. The second objective is to determine if type 2 diabetes status (type 2 diabetes versus prediabetes or moderate+ risk for type 2 diabetes aka at risk for type 2 diabetes) modifies the effect of eating window timing on glycemic control outcomes. The exploratory objectives include: 1) determine whether sex modifies TRE adherence or the effect of TRE on metabolic changes relative to control; and 2) to compare changes in dietary intake, body weight, and blood pressure within and between early, mid, and delayed TRE. We have the following hypotheses related to these objectives:

• The early TRE window will result in the most favourable glycemic control outcomes but also the lowest participant acceptability followed by mid and delayed TRE.
• There will be larger differences in glycemic control outcomes between the TRE window timings among those with type 2 diabetes compared to those at risk for type 2 diabetes.
• TRE adherence and changes in glycemic control, and weight loss with all TRE window times (relative to control) will be higher in men vs women.
• Energy, carbohydrate, and sugar intake, body weight, and blood pressure will decrease during TRE, but with no differences by window timing.

Inclusion criteria

• Aged 40 years or older
• Body mass index <50 kg/m2
• Have access to an Apple or Android cellphone with Bluetooth.
• Have type 2 diabetes or be at risk for type 2 diabetes (defined as self-report of pre-diabetes, a recent (within 12 months) measure of HbA1c between 5.7 and 6.4%, waist circumference (WC) that is BMI specific; for women: BMI >= 18.5-24.9, WC >= 80cm; BMI >= 25-29.9, WC >= 90cm; BMI >= 30-34.9, WC >= 105cm; BMI >= 35+, WC >= 115cm; for men: BMI >= 18.5-24.9, WC >= 90cm; BMI >= 25-29.9, WC >= 100cm; BMI >= 30-34.9, WC >= 110cm; BMI >= 35+, WC >= 125cm.

Exclusion criteria

• Individuals with type 2 diabetes will be excluded if: (1) currently on >2 monotherapies for diabetes, (2) have had diabetes therapy medication or dosage changes <3 months, (3) self-reported hemoglobin A1c >9.0%, (4) taking exogenous insulin, or (5) taking sulfonylureas
• The following exclusion criteria applies to all potential participants:

• History of or referral for bariatric surgery
• Weight loss >3% in the last 3 months
• Taking antiobesity (weight loss) medications
• Body weight >390lbs
• Diagnosed with severe cognitive disorder that precludes them from giving consent
• Inability or unwillingness to change their eating window to follow those prescribed in the study
• Currently consistently eating during <11.5 hour period .
• Physician-diagnosed eating disorder
• Having a pacemaker or receiving dialysis.
• Not having access to a Lifelabs location.