Witt, Craig R.; Grozier, Corey D.; Killen, Lauren G.; Renfroe, Lee G.; O'Neal, Eric K.; Waldman, Hunter S.

Journal of Strength and Conditioning Research 37(5):p 1117-1123, May 2023. | DOI: 10.1519/JSC.0000000000004353

PURPOSE:

To assess the impact of 4 weeks 16:8 time restricted eating (TRE) on markers of metabolic health and 10-km time trial (TT) performance in middle-aged male cyclists. NOTE: 16:8 means all food and drink intake was confined to 8 hours while the remaining 16 hours was fasting, including sleep.

PROCEDURES:

· Twelve subjects aged 40–60 years, with a Vo2 peak of 41.8 ± 5.6 ml·kg−1·min−1 who followed a 

   habitual Western diet completed a familiarization and 2 experimental trials [PRE] and [POST].

· Following habitual Western diet without TRE, anthropometric measures were assessed, followed by a 

   graded exercise test and 10-km TT completion.

· Subjects then adhered to a 4-week TRE protocol where all calories had to be consumed within a self-

   selected 8-hour window and then returned for repeat testing.

CONCLUSIONS:

· Although self-reported caloric intake did not statistically change PRE to POST, body mass (PRE @ 83.2 

   vs. POST @ 80.7 kg), fat mass (∼2.5 kg), and blood pressure (systolic, 8 mm Hg; diastolic, 4 mm Hg) 

   were all significantly lower POST with no changes in fat-free mass.

· Fat oxidation significantly increased (PRE @ 0.36 vs. POST @ 0.42 g·min−1) following the TRE 

   intervention.

· The 10-km TT performance improved by ∼2 minutes POST (PRE @ 29.7 vs. POST @ 27.4)

· The data demonstrated that middle-aged male cyclists adhering to a 4-week TRE protocol can improve 

   their body composition profile and 10-km TT performance without detriments to fat-free mass.

IN PLAIN ENGLISH:

TRE (the fasting period in particular) allows the body to regenerate, recover, clean out, and improve organ and mitochondrial function throughout the body for optimal health and performance potential.