How Interval Fasting Can Complement Your Strength Training Goals

Interval fasting, also known as intermittent fasting, involves alternating between periods of voluntary fasting and eating. The great thing about fasting is that there are several methods that you can choose from that fit your lifestyle. The most popular approaches include 16/8, 5:2, and alternate-day fasting.

Intermittent fasting has been shown to boost hormone optimization, which can be incredibly effective for improving body composition and overall physique aesthetics. It also kickstarts a phenomenon known as autophagy, which involves replacing old, damaged muscle tissues with new and more productive muscle cells. (1)(2)

Contrary to what most people think, interval fasting isn’t just for weight loss, and sticking to this program in the long term does not necessarily result in muscle loss.

You can combine interval fasts with your strength training program to build muscle and lose fat.

As a personal trainer with over 17 years of lifting experience, I can attest that many elite athletes are switching to intermittent fasting to achieve peak physical conditioning. In this article, I decode the science behind how interval fasting can foster fat loss and help you build muscle.

Nutrient Timing: Maximize Your Strength Training Progress

Building muscle involves packing on new muscle tissue, and adopting an extended fasting regime, which comprises adhering to a strict calorie deficit, might sound counterintuitive. However, this is where careful planning and execution come in.

When you are resistance training, you must time your meals perfectly so you don’t lose any of your hard-earned gains during the fasting window. These are the tips that you must internalize:

Pre-Workout Nutrition

Remember, fasting doesn’t mean deprivation. You must use your meals strategically to fuel your body for optimal gains.

Experts recommend consuming a small, easily digestible meal at least 30 to 60 minutes before your workout to allow your body enough time to extract and circulate the nutrients to all your muscle tissues.

Dr. Mike Israetel (Ph.D. in Sport Physiology) recommends avoiding obsessing over your protein intake pre and post-training as research suggests your daily overall protein intake is more important than trying to time it. (3)

Israetel shares similar sentiments over carbohydrates, with a slight twist:

“The only thing you should be concerned about is having enough carbohydrates in your pre-workout meal and having a lot of carbs in your post-workout meal.” — Mike Israetel

A higher carb intake before a session replenishes your glycogen levels, allowing you to go harder and for longer.

Post-Workout Nutrition

Your muscles are primed and ready to absorb nutrients like a sponge after a workout. You must capitalize on this sweet window to maximize your results.

Many nutrition experts recommend consuming a high-protein, balanced meal within one to two hours of finishing your workout.

While all the chatter about the anabolic window might not be true, skipping a meal after a training session can lead to fatigue and muscle breakdown, which can be counterproductive to our goal.

The ideal meal after a workout should comprise lean protein sources like chicken and fish, complex carbohydrates like brown rice and quinoa, and healthy fats like avocado and nuts.

Importance of Adequate Protein Intake and Meal Frequency

Protein is the building block of muscle and arguably the most important macronutrient for building new muscle tissue. You must prioritize your protein intake during an intermittent fasting diet to ensure optimal gains.

The ideal protein intake for each individual will depend on multiple factors like their age, gender activity level, current fitness levels, and training objectives. Use this calculator to determine the right daily protein intake goal for yourself.

Nonetheless, nutritionists suggest aiming for 1.6 to 2.2 grams of protein per kilogram of body weight daily to maximize muscle gains.

Honestly, hitting this goal is easier said than done on a calorie deficit during an IF diet. You must follow a balanced and meticulously planned diet to ensure you’re hitting all the right markers for optimal muscle growth and fat loss.

Training Consideration While Interval Fasting For Maximal Gains

You cannot train the same way during an IF diet as you would during the bulking phase.

I usually have my personal training clients lower their overall training volume (sets, reps, and weights) and intensity (reps in reserve) while they are on an intermittent fasting diet to lower the feelings of sluggishness and fatigue.

Chronic fatigue can hinder the recovery potential and the final results.

Ideal Workout Time

Many prefer training later in their fasting window as it allows them to refuel soon after their workout when their muscles are the most susceptible to nutrient absorption. It also prevents energy crashes and improves overall functionality and performance.

I encourage you to experiment with different workout times to determine which works best for you and your unique lifestyle.

Science Behind Interval Fasting and Strength Training

Now that you know the basics of intermittent fasting, let’s dive into the science behind how it all works.

Here are the benefits of interval fasting and how they can help you achieve your strength training goals:

Boosts Hormone Production

A 2022 study published in the Nutrients journal suggests that intermittent fasting can help enhance testosterone and growth hormone production, maximizing your muscle gains and fat loss potential. (1)

Insulin is one of the most overlooked aspects when it comes to building muscle.

It is crucial for nutrient uptake, but constantly elevated insulin levels can hinder your fat-burning goals. Regular intermittent fasting can regulate your insulin sensitivity, making your body more efficient at utilizing nutrients and ensuring you store minimal body fat.

Autophagy & Cellular Repair

Your body constantly eliminates old and defective cell parts via a process called autophagy. If your body holds onto a suboptimal cell for an extended period, it will significantly hamper your strength training ambitions.

By removing damaged cell components, interval fasting fosters a conducive environment for rebuilding and repairing muscle tissues, leading to faster recovery and better results. (2)

Enhanced Weight Loss & Athletic Performance

No brownie points for guessing this, but your body turns into a fat-burning furnace during a fast as you are only eating during a short window. Your body uses its stored glycogen reserves to burn as fuel, helping you shed the dreaded spare tire.

This phenomenon increases fat expenditure and helps you achieve the ideal body composition.

It doesn’t end here. Scientific research shows that intermittent fasting can boost your body’s ability to use energy efficiently during your workouts. This not only improves your athletic performance but also your results. (4)

Improved Heart Rate & Reduced Inflammation

Intermittent fasting can help improve blood pressure and resting heart rate. Besides this, interval fasting can also result in other health benefits, like reduced LDL cholesterol levels and increased high-density lipoprotein cholesterol.

How is that, you ask?

Carrying excess weight around your midsection puts a considerable strain on your heart.  Switching to an intermittent fasting diet can maximize weight loss and reduce the risk of heart disease.

Furthermore, intermittent fasting has also been shown to reduce inflammation in the body, which has been linked to heart disease. This also helps maximize recovery after an intense training session. (5)

Better Cognitive Function

Poor diet habits are among the biggest reasons for brain fog and impaired memory function. On the flip side, IF can increase brain-derived neurotrophic factor (BDNF) levels, leading to sharper thinking and better memory. (6)

Plus, this makes your brain more resistant to stress, allowing you to push yourself harder in the workouts, resulting in greater muscle stimulation and subsequent adaptations.

Challenges and Potential Side Effects of Interval Fasting

These are the most common bottlenecks with interval fasting when it comes to maximizing your strength training results:

Managing Hunger 

I won’t sugarcoat it. You will have to deal with considerable hunger pangs during the initial phase of interval fasting —  there is no way around it.

However, you must think of it as mental training, as it is a sign that your body is adapting to the new routine and getting used to employing stored glycogen as the primary fuel source.

Performance Dips

It is not uncommon to experience a slight dip in your physical and mental performance during the first few weeks of interval fasting. Make sure that you are not pushing yourself too hard during the period. Take it easy and allow your body to adapt to this new diet regime.

Dehydration and Electrolyte Imbalances

Drink at least a gallon of water each day to avoid the negative consequences associated with dehydration and electrolyte imbalances. Ensuring optimal water intake will also help you avoid cravings.

Incorporating Strategies Like Carb Cycling or Refeed Days

No matter how bulletproof you think your diet and training plans are, you can still run into a wall. However, there are a couple of strategies that you should know about that can help you break through the plateau:

• Carb Cycling: It involves alternating between high-carb and low-carb days to replenish your glycogen stores, boost performance, and support muscle growth.
• Refeed Days: These are planned higher-calorie and carb days incorporated into your diet to boost your metabolism, replenish your glycogen stores, and improve your hormone levels.

Remember, you must learn to listen to your body to ensure the long-term sustainability of interval fasting. Discontinue your workout or diet if something feels weird or unnatural. Consult your healthcare provider if you are experiencing pain, and it does not subside within a couple of days.

Conclusion

Interval fasting can be an incredibly effective approach for achieving your strength training goals of losing fat and building muscle simultaneously. However, it requires following a personalized routine to achieve optimal results.

Like any other transformation program, you must stick with a suitable interval fasting regime for at least eight to 12 weeks to achieve noticeable results.

If you have any questions about how interval fasting can help achieve your strength training goals or need help implementing it into your routine, post them in the comments below, and I’ll be happy to help.

References:

1. Cienfuegos S, Corapi S, Gabel K, Ezpeleta M, Kalam F, Lin S, Pavlou V, Varady KA. Effect of Intermittent Fasting on Reproductive Hormone Levels in Females and Males: A Review of Human Trials. Nutrients. 2022 Jun 3;14(11):2343. doi: 10.3390/nu14112343. PMID: 35684143; PMCID: PMC9182756.
2. Bagherniya M, Butler AE, Barreto GE, Sahebkar A. The effect of fasting or calorie restriction on autophagy induction: A review of the literature. Ageing Res Rev. 2018 Nov;47:183-197. doi: 10.1016/j.arr.2018.08.004. Epub 2018 Aug 30. PMID: 30172870.
3. National Institutes of Health. Intermittent dietary restriction may boost physical endurance. NIH Research Matters. December 10, 2024. Accessed December 10, 2024.
4. Wang X, Yang Q, Liao Q, Li M, Zhang P, Santos HO, Kord-Varkaneh H, Abshirini M. Effects of intermittent fasting diets on plasma concentrations of inflammatory biomarkers: A systematic review and meta-analysis of randomized controlled trials. Nutrition. 2020 Nov-Dec;79-80:110974. doi: 10.1016/j.nut.2020.110974. Epub 2020 Aug 12. PMID: 32947129.
5. Elesawy BH, Raafat BM, Muqbali AA, Abbas AM, Sakr HF. The Impact of Intermittent Fasting on Brain-Derived Neurotrophic Factor, Neurotrophin 3, and Rat Behavior in a Rat Model of Type 2 Diabetes Mellitus. Brain Sci. 2021 Feb 15;11(2):242. doi: 10.3390/brainsci11020242. PMID: 33671898; PMCID: PMC7918995.
6. Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. J Int Soc Sports Nutr. 2013 Dec 3;10(1):53. doi: 10.1186/1550-2783-10-53. PMID: 24299050; PMCID: PMC3879660.

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