Time-restricted feeding improves markers of cardiometabolic health in physically active college-age men: a 4-week randomized pre-post pilot study

Time-restricted feeding (TRF) has been shown to improve body composition, blood lipids, and reduce markers of inflammation and oxidative stress. However, most of these studies come from rodent models and small human samples, and it is not clear if the benefits are dependent upon a caloric deficit, or the time restriction nature of TRF. Based off of previous research, we hypothesized that humans following an ad libitum TRF protocol would reduce caloric intake and this caloric deficit would be associated with greater improvements in cardiometabolic health including blood pressure, body composition, blood lipids, and markers of inflammation and antioxidant status compared to an isocaloric TRF protocol. The purpose of this study was to: (1) examine the impact of TRF on markers of cardio-metabolic health and antioxidant status and (2) determine if the adaptations from TRF would differ under ad libitum compared to isocaloric conditions. Twenty-three healthy men were randomized to either an ad libitum or isocaloric 16:8 (fasting: feeding) TRF protocol. A total of 22 men completed the 28-day TRF protocol (mean ± SD; age: 22 ± 2.5 yrs.; height: 178.4 ± 6.9 cm; weight: 90.3 ± 24 kg; BMI: 28.5 ± 8.3 kg/m2). Fasting blood samples were analyzed for glucose, lipids, as well as adiponectin, human growth hormone, insulin, cortisol, C-reactive protein, superoxide dismutase, total nitrate/nitrite, and glutathione. Time-restricted feeding in both groups was associated with significant (P < .05) reductions in body fat, blood pressure, and significant increases in adiponectin and HDL-c. No changes in caloric intake were detected. In summary, the results from this pilot study in metabolically healthy, active young men, suggest that TRF can improve markers of cardiometabolic health.