Effects of time-restricted eating on aerobic capacity, body composition and markers of metabolic health in healthy-male recreational runners: a randomized crossover trial.

BACKGROUND

Optimal nutrition is highly valuable for athletes aiming at maintaining or improving body composition and sports performance. When combined with structured exercise, time-restricted energy intake may represent an effective non-pharmacological approach to achieve these results.

OBJECTIVE

The aim of this study was to investigate the effects of four weeks of time-restricted eating (TRE) vs. four weeks of habitual diet on aerobic capacity, body composition and metabolic health in 18-30 years old males accustomed to endurance running.

DESIGN

This trial utilized a randomized-crossover study design. Participants completed graded exercise tests, body composition scans and fasting blood samples before and after each intervention condition.

PARTICIPANTS/SETTING

Sixteen male physical-education students were recruited and enrolled in the study from the Faculty of Human Kinetics - University of Lisbon in September 2020, in Lisbon, Portugal. One participant was excluded post-one week due to a lack of adherence to the study protocol. Therefore, fifteen participants completed the study and were involved in the final analysis.

INTERVENTION

During the TRE condition, participants consumed two to three meals within an 8-hour eating window (between 1 and 9 p.m.). Only water, tea and coffee (without caloric additives) were permitted to be consumed in the remaining 16 hours per 24-hour time period. During the non-TRE condition, participants consumed their habitual diet without any timing restrictions. The order of the TRE intervention and the habitual diet condition was randomized and counterbalanced, and participants served as their own controls. The participants followed a structured training routine during each dietary condition. Main outcome measures Body composition variables, indices of running aerobic capacity and markers of metabolic health were assessed. Statistical analyses performed One-way repeated measures analysis of variance and covariance were performed to analyse differences between conditions and time with each intervention.

RESULTS

Neither condition elicited observed changes in total body mass, fat mass nor fat-free mass between time points. Moreover, no significant changes were observed for markers of metabolic health. Significant improvements were obtained with both conditions for the first ventilatory threshold, maximum oxygen uptake (VO

CONCLUSIONS

Four weeks of endurance running and TRE, compared to four weeks of endurance running and a habitual diet, in healthy trained 18-30-year-old male recreational runners did not result in observed differences in total body mass, fat mass or fat-free mass. In addition, TRE did not offer any additional benefit for improving submaximal or peak exercise capacity in this population.

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