Time-restricted feeding (TRF) is a novel type of intermittent fasting that involves eating within a daily period of 10 hours or less, followed by fasting for at least 14 hours daily. Several studies in rodents report that TRF reduces body weight, improves blood sugar control, and reduces the risk of cardiovascular disease-even when food intake is matched to the control group or no weight loss occurs. Preliminary evidence suggests that TRF may also increase weight loss, fat loss, and reduce the risk of diabetes and cardiovascular disease in humans. This study will test whether TRF enhances fat loss and increases weight loss in adults with obesity, relative to conventional dieting alone. In addition, this study will determine whether TRF reduces risk factors for type 2 diabetes and cardiovascular disease and will measure the feasibility and acceptability of TRF. In conjunction with the parent study described above, four ancillary studies will be conducted: 1. Effect of weight loss on nitrogen metabolism and bacteria in the mouth. The primary endpoints for this ancillary study are plasma and salivary nitrate and nitrite, and the secondary endpoints are salivary nitrate reductase activity and salivary bacterial abundance. 2. Effect of weight loss on several biomarkers related to kidney stones. The primary endpoint for this ancillary study is urinary oxalate, and the secondary endpoints are urinary citrate, chloride, sodium, potassium, calcium, phosphorus, uric acid, and creatinine. 3. Effect of meal timing on blood pressure regulation and kidney function. The primary endpoints of this ancillary study include urinary aldosterone excretion, sodium, potassium, and endothelin, whereas the secondary endpoints include nitric oxide and albumin. Additional exploratory endpoints include renal injury markers (KIM-1, nephrin, and urine albumin-to-creatinine ratio), measures of reactive oxidative stress (e.g., hydrogen peroxide and TBARs), and urinary exosomes. Urine will be analyzed in 12-hour bins to determine how meal timing affects differentially affects these endpoints during the daytime and nighttime. The effects of weight loss on these endpoints may also be considered. 4. Validation of a meal timing questionnaire to assess the distribution of food intake throughout the day.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
90
Eat all meals between 7 am - 3 pm for an average of ≥6 days per week.
Eat all meals over a 12-hour or longer period for an average of ≥6 days per week.
A structured weight loss program with physical activity recommendations and dietary counseling.
UAB Weight Loss Medicine Clinic
Birmingham, Alabama, United States
Fat loss and lean mass retention
Percent of weight lost as fat, as measured by dual-energy X-ray absorptiometry (DXA). Lean mass retention will be quantified as 100% minus percent of weight lost as fat (i.e., is measured in the same units).
Time frame: 14 weeks
Weight loss
Change in body weight (kg), as measured by scale weight
Time frame: 14 weeks
Absolute changes in body composition
Changes in total fat mass, lean mass, bone mass, and regional values (kg), as measured by DXA. (This will be secondary to the assessment of fat loss and lean mass retention as specified above.)
Time frame: 14 weeks
Fasting glucose
Fasting glucose (mg/dl)
Time frame: 14 weeks
Fasting insulin
Fasting insulin (IU/L)
Time frame: 14 weeks
HbA1c
HbA1c (%)
Time frame: 14 weeks
Lipids
Total cholesterol (mg/dl), LDL cholesterol (mg/dl), HDL cholesterol (mg/dl), and triglycerides (mg/dl)
Time frame: 14 weeks
Blood pressure
Systolic and diastolic blood pressure (mm Hg)
Time frame: 14 weeks
Heart rate
Heart rate in beats per minute
Time frame: 14 weeks
Waist circumference
Waist circumference (cm)
Time frame: 14 weeks
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