Intermittent Fasting (IF) & Exercise

by Mike Wilson & Roberto Gonzalez

You can also view some of Mike & Roberto's work in John Zehren's book

Coach Wilson's 8 Week Challenge
WilsFast Plan

Although IF has been around for a long time, the effects of IF on different exercise methods has not been well studied. However, there is one method of exercise that has remained central to my training for the past 30 years… resistance training! In fact, the majority of my personal training and exercise experience has revolved around resistance training. I have implemented resistance training in various forms from bodybuilding and powerlifting to Olympic weightlifting and CrossFit. I’ve had success using them all to get strong, fast and lean. Despite my extensive experience implementing resistance training protocols, I admittedly lacked the proper nutritional knowledge necessary to maximize my results.

However in my pursuit of knowledge, I came across an abundance of nutritional information available on the internet and I struggled to distill sound nutritional science from all of the noise. With this in mind, I was determined to augment my understanding of proper nutrition to complement my expertise in strength and conditioning. I enrolled in a comprehensive and rigorous 18-week nutrition certification course while simultaneously learning more about IF and how to implement it properly with exercise. Except there was a small issue, all of the information I was reading regarding IF lacked practical, science-based advice on how to implement IF with resistance training. This left me frustrated, confused and with more questions than answers.

While my fasting times varied from day to day, I would typically spend 16-20 hours in the fasted state with a feeding window of 8-4 hours, depending on which phase of IF. Admittedly, there were times that I stopped eating sooner because I was too full to eat my last meal but that allowed me to get a head start on my fast for the next day. After 2 weeks of IF I felt myself getting fuller much faster and made sticking to my low-calorie diet incredibly manageable. I know you’re probably thinking, a low-calorie diet AND manageable, what’s the catch? Well, luckily for us there really isn’t one. When you fast for extended periods of time your body begins to go through some pretty remarkable adaptations, most notably, you feel your stomach begin to “shrink”. Your stomach is a muscle that stretches and contracts just like your biceps stretch and contract during a bicep curl; and just like your biceps, the only time your stomach begins to “shrink” is when you stop stimulating it. The latest science shows that fasting actually modifies the stomach on a cellular level and it begins to lose its willingness to stretch, thus making you feel fuller for longer. 

Science, thermodynamics in particular, has shown us that calorie intake is the driving force behind successfully losing weight (source), but dieting is so much more than calories and calories out. One of the biggest hurdles to overcome as a dieter, as many of you are aware, is the psychological aspect of having to eat less food and exercise more while simultaneously managing all of life’s responsibilities. As a coach, teacher and business owner, IF gave me the ability to focus on my clients, students and family while still achieving my body recomposition goals. Put simply, IF allowed me to have my cake and eat it too!

Before we get into the details of incorporating resistance training with IF, let me provide you with a brief recap of my progress so far. At the start of my journey with IF I weighed a staggering 270 pounds, and in a less than 2 months I had dropped the easiest 28 pounds of my life without compromising my strength or mental sanity.

Enough about me, let’s get into some practical advice to help you reach your fitness goals.

Setting the Stage:

As I mentioned earlier, there is an overwhelming amount of substandard nutritional and exercise information available at your fingertips. Luckily, we’ve done the work for you. The following information is the culmination of 25+ years of hands-on experience reconciled with the latest with the latest in nutritional and exercise science. The majority of the information provided will be aimed at those looking to get as strong as possible, while simultaneously getting as lean as possible.

Training Dogmas:

• The cornerstone increasing muscle mass (hypertrophy) and strength is the principle of progressive overload. Progressive overload, as the name suggests, is a progressive increase in the load or work done by skeletal muscle. Every time you resistance train you introduce an external stimulus on the muscle, following that bout of resistance training the muscle will adapt to that stimulus and it will require an even larger stimulus to ensure the muscle continues growing stronger. Put more simply, as you continue to exercise, the workout that you did on day 1 becomes easier by week 2. Why? Because the muscle learned to adapt to the stimulus source. Now to be clear, this doesn’t mean you need to change your workouts or exercise selection every week in order to be progressively overloading and stimulating the muscle. I generally stick to exercises I enjoy and modify one of 3 variables.
  • Increase weight. This is probably the easiest way to implement progressive overload into your training. For example if during my bench press I performed 3 sets of 8 reps at 185lbs, then the following workout I will aim for 3 sets of 8 reps at 190lbs. While it’s only a 5lb difference, overall, I am moving 120lbs more during my workout compared to the first workout which will allow me to continue increasing my strength.
  • Increase volume. From my first example, I chose to increase the weight to add 150lbs of extra work to stimulate the muscle. You can increase your training volume by increasing your rep range rather than the weight itself. For example, if I benched 3 sets of 8 reps one week for a total of 24 reps at 185lbs, the following week I could do 5 sets of 5 reps at 185lbs for a total of 25 reps. Despite doing only 1 more rep overall, I still moved 185lbs more overall.
  • Increase intensity. If you’d rather not track every rep, set and weight another simple way to continue to progressively overload the muscle is to increase intensity by altering your rest period. There a few ways of doing this: you can incorporate super-sets (2 antagonistic exercises grouped together, performed in succession with minimal rest time; i.e. tricep extension with bicep curls (source, source) or you can simply decrease your rest time in from 60 seconds down to 45, 30 or 15 seconds.
• You are very unlikely to build muscle while in a calorie deficit (source, source, source).

 Muscle protein synthesis (MPS) is an energetically costly process that is not necessary for day to day survival. Therefore, MPS is reserved for times of energy surplus. However, there is an exception to that rule. If you are an inexperienced lifter (source).

. For the rest of us, our goal will simply be to retain as much muscle mass as possible.  Luckily, resistance training during a calorie deficit provides a protective effect against losing those precious gains.

• For the sake of completion, this does not mean you cannot get stronger! Increases in strength do NOT indicate muscle hypertrophy and conversely, increases in muscle hypertrophy do not indicate an increase in strength.

• If your goal is to maximize strength, hypertrophy (in a calorie surplus) or preserve as much muscle mass during a calorie deficit, you should aim to exercise each body part anywhere from 2-3 times per week. With a classic bodybuilder split that involves working out one body part per day, let’s say chest, we only stimulate muscle growth ONCE every 7 or 8 days. However, by training each body part 2-3 times per week and splitting up the same training volume as the bodybuilding split into 2-3 workouts, you not only recover faster but get a continuous increase muscle protein synthesis every other day (source)! In the context of a calorie deficit, the increases in MPS serves to preserve and remodel existing muscle (to increase strength), remember muscle hypertrophy only occurs in a calorie SURPLUS. Studies suggest that stimulating a muscle group with 8-10 (+/- 2) sets per body part per week will maximize MPS (source).
• You should train to failure at some point in your training schedule but should be limited to 1-2 sets of absolute failure per week per body part. Training to failure too often, especially in a calorie deficit, is very taxing on the body and increases your risk for injury.
• I recommend resistance training 4-6 days per week, keeping in mind to hit each body part at least twice per week.
• Your overall goal in a resistance training program should be to induce the most stress that will yield the biggest increase in lean body mass while allowing you to adequately recover.
• As many of you are aware, IF causes a substantial increase in Human Growth Hormone (HGH) secretion. HGH can indirectly protect muscle mass due to the increased lipolysis (breakdown of fat) which preserves muscle protein during a caloric maintenance or surplus. Interestingly, the absence of HGH during a fast increases protein loss by up to 50%, luckily most of you do not have a HGH deficiency and will see increased HGH secretion with IF! Bottom line, without HGH you will lose more muscle than when you have normal levels of HGH, so at best having regular to increased levels of HGH will not increase or decrease the rate of muscle loss in a calorie deficit (source).

• Contrary to popular belief, aerobic/anaerobic exercise is not required to lose weight. However, there is no denying the benefits of cardiovascular health and fitness. There are essentially 2 styles of “cardio”: High Intensity Interval Training (HIIT) and Low Intensity Steady State (LISS). HIIT involves short maximal effort exercises such as sprinting or rowing whereas LISS typically involves walking on the treadmill or using the stair climber. It was previously thought that HIIT was more muscle sparing than LISS, however, new evidence shows no difference between both forms of cardio. Therefore, the choice is entirely personal. HIIT can produce close to 50% more fat lass using less than 1/10^th the time doing LISS (source, source). However, HIIT workouts are physically taxing and can become increasingly difficult to recover from as your body fat % decreases. Additionally, there’s evidence that suggests performing HIIT before resistance training can inhibit resistance training adaptations when performed first, i.e. cardio then resistance training. So for those of you who train primary for strength might want to consider doing HIIT after resistance training (source). (see figure 1.2)
• When it comes to cardiovascular exercise do what you enjoy or whatever works best for your schedule.

Now that we’ve covered the basic principles governing resistance training, let’s talk about how to get the most out of your training while intermittent fasting.

Dieting Dogmas:

• Lucky for us, studies show that muscle does not spontaneously atrophy to a significant or even notable extent during an 18-20 hour. While I would not recommend training without a good pre or post workout meal, you can rest assured that your hard-earned muscle will still be preserved. Interestingly, there researchers observed an increase in muscle protein breakdown with decreased meal frequency (IF) compared to consuming 3-4 protein rich (>20-25g PRO) meals evenly spread throughout the day (source, source, source, source).
• There is considerable evidence suggesting the onset of muscle protein breakdown begins to increase after a 15-30 hour fast and continues to increase as the fast extends. Moreover, fasts greater than 24 hours in duration may lead to a decrease in testosterone and thyroid hormone – potentially resulting in a slowed metabolism (source, source). But before you get alarmed, it’s important to keep mind that most of you will not be fasting for more than 16 hours, in which case the “loss” of muscle mass is negligible in the grand scale of body recomposition changes.
• Since we already know we cannot build muscle in a calorie deficit our goal then is to maximize muscle protein retention. Given the nature of IF, you will undoubtedly miss out from the anabolic effects of consuming 3-4 protein rich meals greater than 20-25 grams of protein evenly spread out throughout the day. However, fat-loss remains unaffected by IF as long as you consume enough total protein during your feeding window (more on this down below), you will have a positive nitrogen balance (source, source). This simply means you are consuming adequate levels of protein and will not see significant losses in muscle mass. (see figure 1.1)
• One of the coolest aspects of IF is its potent influence on Human Growth Hormone (HGH) (source). HGH increases significantly while fasting but its primary purpose is to help break down stored fat but it will not directly stimulate muscle growth or prevent muscle breakdown while in a calorie deficit (source). However, it is important to keep in mind that the increased lipolysis (fat breakdown) observed with increased HGH levels and the amount of fat that is lost is determined by the size of caloric deficit and not by the increased amount of HGH secreted. Put more simply, you are more likely to use stored fat as a fuel source when growth hormone is elevated (source, source, source).  .

• Putting it all together

• Given all of this knowledge, my best recommendation would be to break your fast 1-2 hours before your workout or 1-2 hours after your workout. Studies suggest that eating before a workout improves your workout performance, thereby allowing you to burn more calories and thus fat compared to working out while fasted (source, source, source).
• Deciding to break your fast before or after your workout should be primarily determined by the difficulty of your training day. For example, if your workout program involves taxing compound movements such as deadlifts or squats, it would be wise to consume a protein and carbohydrate rich meal 1-2 hours before your workout. (see figure1.2) Research shows that post-workout carbohydrate consumption provides energy for training, replenishes muscle glycogen stores and facilitates amino acid uptake into muscle cells. In conjunction with protein, this results in a 20-50% increase in muscle protein synthesis (source).
• As a gentle reminder, there is no fat-loss advantage to working out in a fasted state (source). For those that are curious, there is also no difference between consuming a protein and carbohydrate rich meal pre or post-workout in terms of muscle protein synthesis (source, source, source). Put more simply, whether you chose to break your fast before or after your workout does not have an impact on muscle protein preservation. My baseline recommendation for a pre or post-workout meal should be comprised of at least 20-25 grams of protein with an equal or doubled amount of carbohydrate (40-50g CHO).

  FIGURE 1.1

 FIGURE 1.2

You can also view some of Mike & Roberto's work in John Zehren's book

Coach Wilson's 8 Week Challenge
WilsFast Plan

Side Notes: Empty stomach cardio is completely safe to do during any of these fasting cycles/phases as long as its 30 minutes in length and with a moderate intensity level.

* represents: likely to lose some muscle during cycle

** represents: possible loss of muscle depending on physiological and nutritional factors

*** represents: No Muscle Loss Whatsoever

Michael Wilson

Teacher of Business at Lower Cape May Regional H.S.

Head Strength & Conditioning Coach at LCMRHS

Owner/Head Strength & Conditioning Coach at Cape May Fitness & Sports

Owner - Cape May Dance Company

• “Bachelor of Science in Business Management- University of Phoenix”
• Certified Personal Trainer
• Certified USA Weightlifting Sports Performance Coach
• Certified Weightlifting Performance Coach - NSPA
• Certified Speed & Agility Coach - NSPA
• Certified Program Design - NSPA
• Certified Football Specialist - NSPA
• CrossFit Level 1 Trainer
• Certified Nutrition Coach - Precision Nutrition

Roberto Gonzalez 

“Bachelor of Science in Biochemistry - University of Delaware” “Certificate in Advanced Pre-Medical Sciences - Cooper Medical School of Rowan University  “Certificate in Biochemistry - Harvard Medical School” “Certificate in Physiology - Harvard Medical School” “Certificate in Genetics - Harvard Medical School” “Certificate in Immunology - Harvard Medical School” or you can just sum them up as one as “ Certificate in Medical Sciences - Harvard Medical School”

You can also view some of Mike & Roberto's work in John Zehren's book

Coach Wilson's 8 Week Challenge
WilsFast Plan