A recent systematic review has shed light on the effects of intermittent fasting on sports performance, revealing that the popular dietary strategy does not significantly impair athletic abilities. In order to determine whether intermittent fasting could be a practical option for athletes, a team of researchers from several Spanish universities examined various aspects of physical performance, including aerobic and anaerobic capacity, strength, power, and body composition. The findings were published in the journal Nutrients.
The practice of intermittent fasting, which alternates between eating and fasting periods, has grown significantly in popularity in recent years as a successful way to lose weight and improve overall health. But its impact on sports performance has been a subject of debate, with concerns about whether such a dietary approach might compromise athletes’ physical abilities.
The review scrutinised 25 research articles that focused on adult human athletes engaged in different types of intermittent fasting. These studies covered a broad range of physical capacities, from endurance and strength to power, and also considered the effects on body composition, such as muscle mass and fat reduction.
One of the key findings from the review was that intermittent fasting could positively influence body composition by reducing fat mass while preserving lean muscle mass. This aspect of intermittent fasting is particularly appealing to athletes who aim to optimise their body composition for better performance. By lowering fat mass, athletes might experience improvements in power-to-weight ratio, which could be beneficial in sports requiring speed and agility.
However, the review also highlighted that while intermittent fasting can lead to improvements in body composition, it does not seem to have a pronounced effect on sports performance metrics such as aerobic and anaerobic capacity or muscle strength. In other words, athletes practising intermittent fasting are unlikely to see significant enhancements or declines in their physical performance due to the diet alone.
The researchers noted that the timing and type of fasting play crucial roles in determining the outcomes. For instance, the study referenced fasting during Ramadan, where fasting periods can last between 12 and 18 hours with no food or liquid intake during daylight hours. This type of fasting was associated with more pronounced challenges in maintaining performance, particularly in elite athletes, due to the combined effects of fasting and changes in sleep and hydration patterns. In contrast, time-restricted feeding, typically involving a 16-hour fast and an 8-hour eating window, did not show significant detriments to athletic performance.
