Intermittent fasting (IF) has gained significant popularity as a weight loss strategy in recent years. By restricting eating to specific time periods, many individuals find it easier to consume fewer calories and maintain a healthy weight.
However, for those who aspire to build muscle while losing fat, there is a concern about whether intermittent fasting can hinder muscle growth. So, what does the research say? Can we effectively combine intermittent fasting and muscle gain, or should we focus on one goal at a time?
To understand the impact of intermittent fasting on muscle growth, let’s delve into the biology of muscle. Skeletal muscle cells, also known as muscle fibres, are responsible for voluntary movement and are the type of muscle cells we focus on when aiming to gain muscle through exercise. These cells can increase in length by incorporating new myoblasts, which are precursor cells for muscle fibres. This process increases girth and is typically observed in weightlifters.
Muscle growth is regulated by various molecular mechanisms, one of which involves a protein called myostatin. Myostatin acts as a negative feedback signal, inhibiting excessive muscle growth. Mutations in the myostatin gene have been found to increase muscle mass in animals such as cattle and mice. Additionally, other mechanisms contribute to muscle growth, and the balance of these signals determines whether muscle cells grow, shrink, or remain the same.
Now, let’s address the question of whether intermittent fasting inhibits muscle growth. Several systematic reviews and meta-analyses have been conducted to evaluate the effects of intermittent fasting on muscle gain and athletic performance. In particular, research has focused on time-restricted fasting, where individuals fast for a specific duration each day and consume food within a restricted window.
Meta-analyses examining the effects of time-restricted fasting on muscle gain from resistance training consistently found that it did not impede gains in muscle mass. In fact, some studies even suggested that time-restricted fasting could improve muscle gains. These findings indicate that individuals can engage in resistance training and intermittent fasting simultaneously without compromising muscle growth.
Furthermore, time-restricted fasting has shown positive effects on aerobic capacity (oxygen consumption) without negatively affecting baseline muscle strength. However, it is worth noting that very narrow windows for eating, such as a 20:4 regimen (20 hours of fasting and 4 hours of eating), may lead to muscle loss. Therefore, it is important to strike a balance when implementing time-restricted fasting.
When it comes to the impact of time-restricted fasting on athletic performance, the evidence is more varied and dependent on the specific sport or activity. Some studies have suggested impaired performance among rowers and cyclists, while others have found no detrimental effects on endurance or peak performance and even a slight benefit among young, elite cyclists. The results remain inconclusive and require further investigation.
If your goal is to gain muscle through resistance training, time-restricted fasting appears to be a viable option that does not hinder progress. It can also positively impact aerobic capacity. However, when it comes to sporting performance, caution is advised, especially for high-level athletes. The current body of evidence is still limited and often focuses on overweight individuals or highly fit individuals. More research is needed to fully understand the effects of time-restricted fasting on different sports and activity levels.
It’s important to remember that everyone is unique, and what works for one person may not work for another. If you are considering time-restricted fasting for weight loss and muscle gain, a 16:8 schedule (16 hours of fasting and 8 hours of eating) may be a good starting point. This approach allows for muscle preservation while potentially improving aerobic capacity. As always, listen to your body, make adjustments as needed, and consult with a healthcare professional or nutritionist before making any significant changes to your diet or exercise routine.
While intermittent fasting has gained popularity as a weight-loss strategy, it does not appear to hinder muscle growth when combined with resistance training. Time-restricted fasting can also enhance aerobic capacity. However, the impact on sporting performance remains uncertain and requires further research. If you decide to try intermittent fasting, do so cautiously and monitor your body’s response. Remember that individual differences exist, and more studies are needed to fully understand the effects of intermittent fasting on different populations and athletic endeavours.
