Unlocking the Muscle-Saving Magic of Intermittent Fasting

Introduction: The Fasting Phenomenon

Intermittent Fasting (IF) has seen a meteoric rise in popularity over the last decade, not just as a weight loss strategy but also as a proposed method for promoting longevity, metabolic health, and even brain health (1).

But for fitness enthusiasts and bodybuilders, a pressing concern remains:

Can we preserve muscle mass during periods of fasting, or are we setting ourselves up for muscle breakdown?

What Happens When We Fast?

The Metabolic Shift

When the body stops receiving external sources of energy (food), it undergoes a metabolic shift.

After depleting glycogen reserves, the body turns to stored fat as its primary energy source, resulting in the production of ketones, which can act as an alternative energy source for the brain (2).

Hormonal Changes

Fasting also triggers a cascade of hormonal changes.

Notably, there's a spike in human growth hormone (HGH) production, which plays a vital role in muscle growth and metabolism (3).

Additionally, fasting can increase norepinephrine levels, which further aids in fat breakdown.

Intermittent Fasting and Muscle Preservation

The Role of HGH

As mentioned, fasting triggers a rise in HGH levels. This hormone not only promotes fat metabolism but also has anabolic properties, potentially counteracting muscle protein breakdown (3).

Protein Conservation

Contrary to popular belief, short-term fasting may not lead to significant muscle breakdown. The body prioritises fat stores for energy during a fast, especially with the hormonal changes promoting fat metabolism (4).

Autophagy: The Cellular Cleanup

Intermittent fasting can also stimulate autophagy, a process where cells "clean up" damaged components. This process is essential for cellular health and can potentially aid muscle function and longevity (5).

Combining Fasting with Resistance Training

One of the significant concerns surrounding intermittent fasting is the potential loss of hard-earned muscle mass. Fortunately, resistance training acts as a buffer against this potential pitfall.

Engaging in strength-building exercises, such as weight lifting, resistance band exercises, or body-weight movements, can substantially aid in muscle preservation.

During fasting, the body is keen on conserving energy.

However, when you introduce resistance training, you send a potent signal to your body that your muscles are essential and need to be preserved.

As such, even though the body is in an energy-conserving mode due to fasting, it becomes more inclined to use stored fat for energy rather than breaking down muscle tissue.

Studies have highlighted that resistance training during intermittent fasting can not only maintain muscle mass but can even enhance muscle strength and promote growth (6).

It's also worth noting that the post-workout period becomes a prime window for nutrient absorption.

This can further augment the benefits of resistance training, especially when it aligns with your eating window.

Personally, I do my weight training at the end of a 24-hour fast whilst my HGH levels are elevated then I break it with a post-workout shake followed by a balanced wholefood meal.

Proper Nutrition During Eating Windows

The essence of intermittent fasting lies in the periods you're not eating, but this doesn't downplay the significance of your eating windows.

In fact, what you consume during these times can make or break your muscle preservation efforts.

First and foremost is protein intake.

Protein provides the building blocks (amino acids) necessary for muscle repair and growth.

Especially during intermittent fasting, it's vital to ensure you're consuming adequate amounts of protein to support recovery and muscle maintenance.

Sources can include lean meats, fish, eggs, dairy, legumes, and plant-based alternatives.

But it's not just about protein.

Overall caloric intake is crucial too.

Even if you're fasting to lose weight, it's essential to ensure you're not in a too-aggressive caloric deficit, which could lead to muscle catabolism.

Instead, aim for a moderate calorie deficit, if weight loss is the goal, ensuring you're still nourishing your body with all the essential macronutrients, including healthy fats and complex carbohydrates.

Lastly, micronutrients play a pivotal role.

Vitamins and minerals support a range of bodily functions, including those involved in muscle function and recovery. Thus, incorporating a diverse range of fruits, vegetables, whole grains, and lean proteins can ensure you're not missing out on these critical components.

In essence, while the fasting periods in intermittent fasting are undeniably essential, the nutrition you provide your body during eating windows is just as crucial.

Properly fueling your body ensures you reap the benefits of fasting while minimising potential drawbacks.

Conclusion: Striking the Balance

Intermittent fasting offers numerous health benefits, but muscle preservation remains a top concern for many.

With the metabolic and hormonal shifts promoting fat metabolism and anabolic processes, combined with resistance training and proper nutrition, muscle maintenance is not only possible but also likely.

As always, it's vital to listen to one's body and consult with health professionals when adopting new dietary strategies.

1. Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing Research Reviews, 39, 46-58.
2. Cahill Jr, G. F. (2006). Fuel metabolism in starvation. Annual Review of Nutrition, 26, 1-22.
3. Hartman, M. L., Veldhuis, J. D., Johnson, M. L., Lee, M. M., Alberti, K. G., Samojlik, E., & Thorner, M. O. (1992). Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men. The Journal of Clinical Endocrinology & Metabolism, 74(4), 757-765.
4. Zauner, C., Schneeweiss, B., Kranz, A., Madl, C., Ratheiser, K., Kramer, L., ... & Lenz, K. (2000). Resting energy expenditure in short-term starvation is increased as a result of an increase in serum norepinephrine. The American Journal of Clinical Nutrition, 71(6), 1511-1515.
5. Alirezaei, M., Kemball, C. C., Flynn, C. T., Wood, M. R., Whitton, J. L., & Kiosses, W. B. (2010). Short-term fasting induces profound neuronal autophagy. Autophagy, 6(6), 702-710.
6. Tinsley, G. M., & La Bounty, P. M. (2015). Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, 73(10), 661-674.
7. Mero, A. (1999). Leucine supplementation and intensive training. Sports Medicine, 27(6), 347-358.