Background: Intermittent fasting has gained substantial popularity in the past decade. The most popular form of intermittent fasting is time restricted eating (TRE) , which involves eating within a 4-to-10-hour window and water fasting for the rest of the day. Short-term studies (2 months) indicate that TRE produces mild reductions in body weight and markers of glucose regulation. What remains unknown is whether longer durations of TRE (6-months) can lead to even greater improvements in these diabetes risk factors. In addition, whether TRE is more effective than daily calorie restriction (CR) for improving these endpoints, also remains unknown.

Objective: The purpose of this study was to compare the effects of 8-h TRE versus daily CR on body weight, body composition, and markers of glucoregulation, in adults with obesity.

Design: Participants were randomized to 1 of 3 groups for 6-months: 8-h TRE (n = 24, 12-8pm eating window, 8pm-12pm fasting window) , CR (n = 22, 25% energy restriction daily) , or a control (n = 19, no food or meal timing restrictions) .

Results: Weight loss was not significantly different between the TRE (-3.4 ± 0.7%) and CR group (-4.9 ± 1.4%) by month 6. Only the CR group experienced significant weight loss (P = 0.02) versus controls (-0.7 ± 1.1%) . Changes in fat mass, lean mass, and visceral fat mass were not significantly different between groups post-treatment. Likewise, no significant changes in fasting glucose, fasting insulin, or HbA1c were observed. Changes in insulin resistance (assessed via HOMA-IR) did not differ between TRE (-0.50± 0.35 %) , CR (-0.56 ± 0.39 %) , or controls (0.37 ± 0.43%) .

Conclusions: These findings suggest that TRE does not produce greater weight loss than traditional dieting (CR) over 6-months. Our findings also show that neither diet had any beneficial effect on body composition of markers of glucoregulation, versus controls, in adults with obesity.


S.Cienfuegos: None. S.Lin: None. K.Gabel: None. M.Mcstay: None. A.Mulas: None. K.Varady: None.


R01DK128180 , NIH (NIDDK)

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