A 12-month randomized, controlled, parallel-arm trial, divided into 2 consecutive periods: (1) 6-month weight loss period; and (2) 6-month weight maintenance, will be implemented. Adults with obesity will be randomized to 1 of 3 groups: (1) 8h-TRE, ad libitum food intake from 12pm to 8 pm, fasting from 8 pm to 12 pm daily, (2) CR, 25% energy restriction every day; or 3) control, ad libitum food intake daily, eating within more than 10 hours per day.
Time restricted eating (TRE) has become a popular weight loss regimen. The sudden rise in popularity of TRE is mostly likely due to is its sheer simplicity, and the fact that it does not require individuals to count calories in order to lose weight. Participants are simply asked to consume all food within a specified time frame and fast with energy free beverages for the remaining hours of the day. Evidence shows that when people with obesity limit their eating window to 6 to 8 hours per day, they naturally reduce energy intake by 350-500 calories. From a clinical standpoint, these findings are paramount. One of the main reasons for subject attrition with traditional dieting, i.e. daily calorie restriction (CR), is frustration with having to count calories every day. TRE regimens are able to side-step this requirement by allowing participants to simply "watch the clock" instead of monitoring calories, while still producing significant weight loss and metabolic health improvements. This feature of TRE has the potential to improve long-term adherence to the diet, and in turn produce lasting weight control in adults with obesity. Accordingly, we conducted a one-year, randomized, controlled trial to compare the effects of late TRE (eating all food between 12:00 pm to 8:00 pm, without calorie counting), versus CR (25% energy restriction daily), and a control group eating over a period of 10 or more hours, on body weight and metabolic risk factors in a diverse group of American adults with obesity. We hypothesized that the TRE group would achieve greater weight loss, and experience more pronounced improvements in insulin sensitivity during the 6-month weight loss phase, compared to CR and control participants. We also hypothesized that the TRE group would better maintain their weight loss and sustain their improvements in insulin sensitivity during the 6-month weight maintenance phase, when compared to the CR and control participants.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
90
Ad libitum food intake from 12-8 pm every day Fasting from 8-12 pm every day (16-h fast)
25% energy restriction every day
University of Illinois Chicago
Chicago, Illinois, United States
Change in Body Weight
Measured by an electronic scale
Time frame: Measured at month 0 and 12
Change in Fat Mass
Measured by DXA
Time frame: Measured at month 0 and 12
Change in Insulin Resistance
Measured by Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). Values above 2.5 generally considered an indicator of insulin resistance. Higher values indicate greater insulin resistance while lower values indicate lower insulin resistance. HOMA-IR = \[glucose (mmol/L) × insulin (μU/L)\]/22.5.
Time frame: Measured at month 0 12
Change in Insulin Sensitivity
Measured by Quantitative Insulin Sensitivity Check Index (QUICKI). QUICKI calculated as = 1/\[log (fasting insulin, U/ml) + log (fasting glucose, mg/dl)\]. Higher scores (typically \> 0.45) indicate high insulin sensitivity. Lower scores (generally ≤ 0.33 or 0.34) indicate decreased insulin sensitivity and an increased risk for insulin resistance or type 2 diabetes.
Time frame: Measured at month 0 and 12
Change in Fasting Glucose
Measured by a commercial lab (Medstar, IL)
Time frame: Measured at month 0 and 12
Change in HbA1c
Measured by a commercial lab (Medstar, IL)
Time frame: Measured at month 0 and 12
Change in Fasting Insulin
Measured by a commercial lab (Medstar, IL)
Time frame: Measured at month 0 and 12
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Change in Systolic Blood Pressure
Measured by a blood pressure cuff
Time frame: Measured at month 0 and 12
Change in Diastolic Blood Pressure
Measured by a blood pressure cuff
Time frame: Measured at month 0 and 12
Change in LDL Cholesterol
Measured by a commercial lab (Medstar, IL)
Time frame: Measured at month 0 and 12