Effects of 6‐weeks of Time‐Restricted Feeding in Normal Weight Middle‐Aged and Older Adults

Abstract

Calorie restriction (CR) improves multiple indicators of healthspan and physiological function in humans. However, CR is contraindicated in normal‐weight middle‐aged and older (MA/O) adults because it induces deleterious adaptations, such as reductions in body mass (including skeletal muscle mass) and bone mineral density (BMD). Time‐restricted feeding (TRF), which involves consuming all calories within an 8–10‐hour window and fasting for the remainder of the day, has the potential to maximize the benefits of CR while minimizing these possible adverse effects in normal‐weight MA/O adults. We performed a randomized controlled crossover clinical trial to evaluate the feasibility, tolerability and lack of adverse changes in body composition and BMD following six weeks of TRF vs. normal feeding (NF) in normal‐weight MA/O adult men and women (n=22, 67±6 years). A secondary aim was to explore the potential efficacy of TRF for improving select indices of healthspan and physiological function. Adherence to TRF was excellent with all subjects successfully reducing their eating window from 11.7 ± 0.3 hours/day to within 8 hours/day (7.6±0.1 hours/day, p<0.05). Compared with NF, all subjects maintained their regular daily energy intake during TRF, with no significant changes in macronutrient composition or overall diet quality, as assessed using the Healthy Eating Index (HEI; NF= 63±3 vs. TRF= 61±2, p>0.05). TRF was well‐tolerated with no increases in self‐reported desire to eat, satiety, or stomach fullness (all p>0.05 vs. NF) and interestingly, lower feelings of hunger (p<0.01 vs. NF). Importantly, TRF did not affect body mass, BMD or body composition (all p>0.05 vs. NF). TRF improved two indices of cardiorespiratory fitness, including a reduced heart rate during submaximal exercise (p<0.05) and increased distance traveled during a 6‐minute walk test (NF=570±12 m vs. TRF=585±11 m, p<0.05). Glucose tolerance, assessed during a 2‐hour oral glucose tolerance test in a subset of subjects (n=16), also improved with TRF (NF=15,500±300 mg/dL x min vs. TRF=14,500±200 mg/dL x min, p<0.05). These findings suggest that TRF is feasible and well‐tolerated in normal‐weight MA/O adults and is not associated with adverse changes in body composition or BMD. Moreover, TRF may improve cardiorespiratory fitness and glycemic control, two important indicators of healthspan and future risk of chronic disease, disability, and/or frailty. Thus, TRF may be a practical alternative to conventional CR for improving healthspan in normal‐weight MA/O adults.Support or Funding InformationSupported by Aging T32 AG000279This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.