Time-restricted eating effects on performance, immune function, and body composition in elite cyclists: a randomized controlled trial

J Int Soc Sports Nutr. 2020 Dec 11;17(1):65. doi: 10.1186/s12970-020-00396-z.

Abstract

Background: Although there is substantial interest in intermittent fasting as a dietary approach in active individuals, information regarding its effects in elite endurance athletes is currently unavailable. The present parallel randomized trial investigated the effects of a particular intermittent fasting approach, called time-restricted eating (TRE), during 4 weeks of high-level endurance training.

Methods: Sixteen elite under-23 cyclists were randomly assigned either to a TRE group or a control group (ND). The TRE group consumed 100% of its estimated daily energy needs in an 8-h time window (from 10:00 a.m. to 6:00 p.m.) whilst energy intake in the ND group was distributed in 3 meals consumed between 7:00 a.m. and 9:00 p.m. Fat and fat-free mass were estimated by bioelectrical impedance analysis and VO2max and basal metabolism by indirect gas analyzer. In addition, blood counts, anabolic hormones (i.e. free testosterone, IGF-1) and inflammatory markers (i.e. IL-6, TNF-α) were assessed.

Results: TRE reduced body weight (- 2%; p = 0.04) and fat mass percentage (- 1.1%; p = 0.01) with no change in fat-free mass. Performance tests showed no significant differences between groups, however the peak power output/body weight ratio (PPO/BW) improved in TRE group due to weight loss (p = 0.02). Free testosterone and IGF-1 decreased significantly (p = 0.01 and p = 0.03 respectively) in TRE group. Leucocyte count decreased in ND group (p = 0.02) whilst the neutrophils-to-lymphocytes ratio (NLR) decreased significantly (p = 0.03) in TRE group.

Conclusions: Our results suggest that a TRE program with an 8-h feeding window elicits weight loss, improves body composition and increases PPO/BW in elite cyclists. TRE could also be beneficial for reducing inflammation and may have a protective effect on some components of the immune system. Overall, TRE could be considered as a component of a periodized nutrition plan in endurance athletes.

Trial registration: This trial was retrospectively registered at clinicaltrials.gov as NCT04320784 on 25 March 2020.

Keywords: Elite cyclists; Endurance; Immune system; Inflammation; Intermittent fasting.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Athletes*
  • Athletic Performance / physiology*
  • Basal Metabolism
  • Bicycling / physiology*
  • Body Composition / physiology*
  • Creatinine / blood
  • Diet
  • Electric Impedance
  • Energy Intake
  • Fasting / physiology*
  • Humans
  • Immune System
  • Insulin-Like Growth Factor I / analysis
  • Interleukin-6 / blood
  • Leukocyte Count
  • Lymphocyte Count
  • Male
  • Sports Nutritional Physiological Phenomena
  • Testosterone / blood
  • Time Factors
  • Transforming Growth Factor alpha / blood
  • Weight Loss
  • Young Adult

Substances

  • Interleukin-6
  • Transforming Growth Factor alpha
  • Testosterone
  • Insulin-Like Growth Factor I
  • Creatinine

Associated data

  • ClinicalTrials.gov/NCT04320784