Time Restricted Feeding (4-hour versus 6-hour) for Weight Loss in Obese Adults


Time restricted feeding (TRF) is a form of intermittent fasting that has gained substantial popularity over recent years as a weight loss regimen. Despite its growing popularity, very few studies have examined the weight loss efficacy of this diet. TRF involves eating within a specific window of time each day, and water fasting for the rest of the day. The goal of this study was to compare the effects of a 4-h TRF versus 6-h TRF on body weight, metabolic disease risk factors, inflammation, and sleep, in adults with obesity. Subjects with obesity (n = 58) were randomized to 1 of 3 groups: 1) 4-h TRF (ad libitum feeding between 3pm to 7pm, water fasting between 7pm to 3pm), 2) 6-TRF (ad libitum feeding between 1pm to 7pm, water fasting between 7pm to 1pm), or 3) control group (usual diet with no meal timing restrictions) for 8 weeks. Results from this study show that 8 weeks of 4-h and 6-h TRF decreases body weight by -3.2% and -3.2%, respectively, relative to controls. Subjects were adherent to the prescribed eating window on 6.2 days per week, and this level of adherence remained constant throughout the 8-week trial. Our findings also indicate that reducing the daily eating window to either 4-h or a 6-h decreases caloric intake by ~550 kcal/d, without intentional calorie counting. Both TRF interventions produced significant reductions in fasting insulin, HOMA-IR (measurement of insulin resistance) and oxidative stress, versus controls. However, other metabolic disease risk parameters such as plasma lipids, blood pressure, and inflammation, remained unchanged. As for sleep, sleep quality and duration remained unchanged in all groups. Our results also suggest that TRF is a safe diet therapy that does not induce any significant adverse effects. These data offer promise for the use of shorter (4-h and 6-h) eating windows as safe and effective weight loss regimens in adults with obesity. However, longer-term, larger-scale randomized controlled trials will be required before solid conclusions can be reached

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