According to a study by researchers at the Universitat Oberta de Catalunya (UOC), time-restricted feeding can have a positive impact on athletes in terms of both their health and performance. The effects of time-restricted eating – where food intake is permitted within a restricted window ranging from 3-4 to 10-12 hours – have been widely studied in the general population, where they have been shown to increase life expectancy, but there is little evidence on its positive effects on high-performance athletes.
The study – "Effect of time-restricted feeding on aging and performance of athletes (systematic review)" – was led by Òscar Sánchez, who is both a community dietitian and nutritionist working in primary care and a researcher, as part of his final project for the Master's Degree in Food for Physical Activity and Sport at the UOC. According to Sánchez, "the evidence reveals that time-restricted eating for health can be recommended to both athletes and the general public".
The research involved a systematic review published as open access in the Spanish journal Revista Española de Nutrición Comunitaria. It has been carried out with Laura Esquius, director of the Master's Degree, researcher at the Research Group in Epidemiology and Public Health in the Digital Health Context (Epi4health, which is attached to the Digital Health, Health and Well-being Research Unit) and member of the Faculty of Health Sciences. Daniel Badia-Martínez, a member the master's degree's teaching staff and Sánchez's tutor for the study, was also involved in the project.
"Time-restricted feeding could be recommended to athletes, albeit with caution. Some of the studies reviewed have found that it can be effective in improving or maintaining performance without significant adverse effects, especially when combined with high-intensity interval training (HIIT)," said Esquius.
Combining HIIT with time-restricted eating has been shown to yield greater improvements in performance, "although more research is needed to establish safe and effective guidelines for high-performance athletes," said Esquius. The review shows that, in endurance sports, time-restricted feeding may improve body composition and boost immunity without impairing performance. The researchers also noted that it could help prevent metabolic disorders that can arise when high-performance athletes retire from professional sport.
"The study suggests that this may be a useful strategy, particularly in relation to health and ageing, where certain hormonal and molecular aspects appear to be improved," said Badia-Sánchez, who also highlighted the need for further research in this field to build up more evidence.
The study involved a systematic review of two databases of medical studies – Medline and Cochrane – based on a number of keywords aimed at obtaining scientific evidence on time-restricted eating and its effects on sports performance and ageing in athletes. The keywords used for search 1 were: feeding time OR time restricted feeding AND exercise AND health. The keywords used for search 2 were: feeding time OR time restricted feeding AND performance AND health.
The researchers found four studies carried out on athletes and 14 examining the effects of time-restricted eating on the general population, including both healthy individuals and those with illnesses such as obesity, type 2 diabetes, multiple sclerosis, metabolic syndrome or metabolic dysfunction-associated fatty liver disease (MAFLD).
The researchers view this study as the first step towards finding new nutritional strategies in the field of sport to improve health, performance and life expectancy.
Time-restricted feeding to slow down ageing
Time-restricted eating reduces biological age (as measured by the epigenetic clock test), increases levels of brain-derived neurotrophic factor (a protein that increases neuroprotection and neuronal regeneration) and LC3A and SIRT-1 (proteins involved in longevity and autophagy, a process under which cells break down damaged proteins, which are then recycled for important cellular functions, such as destroying viruses and bacteria and preventing the development of cancerous cells). "Preliminary studies have shown that time-restricted feeding has potential for reducing oxidative stress and inflammation, key factors in ageing, for both athletes and the general population," said Esquius, who specializes in sports nutrition and teaches on a number of programmes at the UOC.
Most of the studies in the review point to significant metabolic benefits and anti-inflammatory effects, including improvements in metabolic syndrome and glycaemic control. Time-restricted eating also reduces fat mass and increases lean body mass, improves body composition and regulates hunger and satiety signals. However, these benefits arise only when used in combination with a balanced diet and a healthy lifestyle.
"As a general rule, people should 'eat during daylight hours and not when it's dark outside,' which is enough to restrict the eating time window to about 12 hours. This can be a healthy habit for the vast majority of people, except for those with diseases for which it is contraindicated, such as diabetes, eating disorders or chronic decompensated conditions," said Badia-Martínez.
Building up evidence in primary care settings
Amid medical researchers' growing interest in time-restricted feeding due to its proven health benefits, the authors of the study stressed the need for further work in this line of research to confirm the evidence of its positive impact, especially in the field of sport, where studies are more limited. In Òscar Sánchez's opinion, "these results are a positive step forward […] We've observed that time-restricted eating has a positive impact on athletes' health and ageing without adverse effects on their performance. This is key, because it's something that no athlete would be willing to give up."
According to Sánchez, the next steps are proving the benefits of time-restricted feeding and conducting further research to explore its potential uses in practice. "I'd like to be able to show this dietary technique (time-restricted eating) to my fellow doctors and nurses, teach them more about it and prove its potential in a randomized control trial (RCT)," he said.
This study is aligned with the UOC's research mission on Digital health and planetary well-being and contributes to UN Sustainable Development Goal 3, Good Health and Well-being.
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