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Flexible Dieting with Intermittent Fasting

by Michael Petresky on November 8, 2013

Last week I spoke of how it is important to never be so strict in what you believe to be true that you cannot consider an alternative  viewpoint, and the importance of  challenging your beliefs. When I learned of intermittent fasting my beliefs took a blow as IF contradicted a lot of what i believed to be true regarding my approach to nutrition, and what I preached to others. Read on to learn what i consider to be the holy grail of fat loss and body recomposition.

IF Defined:

Intermittent fasting (IF) is a pattern of eating that alternates between periods of fasting (usually meaning consumption of water and sometimes low-calorie drinks such as black coffee) and non-fasting.”

The Myths

  • A high meal frequency (think 4-6 small meals/day every 2-3 hours) boosts your metabolism.
  • Small, frequent meals help control appetite.
  • Small, frequent meals help control blood sugar levels.
  • Fasting (skipping meals) puts the body into ‘starvation’ mode.
  • Protein should be consumed every 2-3 hours to prevent catabolism (muscle breakdown), and keep the body in an anabolic state.
  • The body cannot digest more than 30g of protein in one feeding.
  • Fasting and skipping meals causes muscle loss.
  • Breakfast is the most important meal of the day. Skipping breakfast is bad and will make you fat.
  • Fasted training will prevent you from making gains in strength and muscle.
  • Fasted training will lead to losses in strength and muscle.

The Benefits:

  • Reduced blood lipids and LDL (bad) cholesterol.
  • Reduced blood pressure.
  • Reduced risk of cancer.
  • Increased cell repair.
  • Increased fat burning.
  • Increased growth hormone release.
  • Increased metabolic rate.
  • Improved appetite control.
  • Improved blood sugar control.
  • Improved nutrient partitioning (nutrients to muscle rather than fat).

Your Options:

  • Leangains (the 16-8 protocol):

Giving credit to Martin Berkhan for creating this and initiating the spread of IF across the internet. Leangains, also known as the 16-8 protocol is a 16 hour fast with an 8-hour feeding window. An example would be setting your feeding window from 12pm to 8pm. By doing this you keep the majority of your fast during the time you are sleeping, and you’re only really having to fast while awake during the morning. Essentially you’re skipping breakfast and making sure your last meal for the day is no later than 8pm.
*Note: Women do better with a shortened fast and longer feeding window (try 14-10).

  • Eat-Stop-Eat:

Giving credit to Brad Pilon for creating this and furthering the truth of fasting for body recomposition. With this protocol instead of fasting daily you choose 1-2 days per week to fast for 24 hours. It can be any day of the week that suits your schedule best and any time frame. For example, you can fast from Sunday morning to Monday morning, or from Saturday night to Sunday night. Try both and see what you feel best following. Try eating a large meal Saturday evening, and fasting until Sunday evening. You would end the fast with a large meal before bed on Sunday, and resume a ‘normal’ eating schedule Monday. For the rest of the week, focus on healthy food choices such as lean meats, vegetables, fruits, and whole grain carbohydrates.

  • The Warrior Diet:

This is a 20 hour fast with a 4 hour feeding window. You’re allowed small amounts of food during the fast (think hunter-gatherers) such as small portions of nuts or strips of animal protein. The bulk of your daily calories will be consumed during the 4 hour feeding window that would usually be placed at the end of the day before bed, but like all of these protocols this is flexible and can be arranged to suit your schedule.

Keep it flexible:

How you fasted on Monday does not have to determine how you fast on Friday.

Let’s say Monday you have morning classes or work, and go to bed before midnight. Eat your last meal by 9pm. Wake up at 8am, fast through the morning, and break the fast at 1pm. Your feeding window here is from 1-9pm.

Let’s say Friday you plan to be up late, go out with friends for beer, and drunkenly eat pizza afterwards. Simply extend your fast until later in the day, and move your feeding window. Now you’re fasting until 6pm, and your feeding window is from 6-2am. This is also how a night-owl or someone who works very late could structure their fasts.

Intermittent Fasting is the holy grail for those seeking weight loss or body recomposition. By giving yourself a ‘feeding window’ you can better manage your daily calorie intake by limiting the amount of time you have each day to feed. I’ve found that after my first meal (whether it is a small snack or a complete meal) my  appetite is increased thereafter. By postponing your first meal you are able to better control your hunger, and thus your overall calorie intake, which is the primary factor that dictates whether or not you increase, decrease, or maintain your bodyweight.

You Will Adapt:

Say you wake up and eat breakfast at 8am, and a few hours later you start to feel hungry again for more food. This is not the case if you skip breakfast in the morning. You will notice that your initial hunger quickly fades and you can go on about your day not feeling hungry. Our bodies love routine and patterns. If you habitually eat soon after waking up your body becomes accustomed to this, and this is why you get hungry immediately upon waking. If instead you adopt a habit of not eating in the morning your morning hunger pangs will become nonexistent.


Another benefit of fasting is you will be more alert. This is great because if I am awake in the morning it is usually because I have work to complete. If you think that going 4-6 hours without food in the morning will be difficult there are a few tricks you can implement. Try to keep yourself busy. The fast is a time for getting shit done – not – sitting around brooding about how hungry you are and how much fasting sucks. Drinking water, black coffee, or green tea is also helpful in mitigating any hunger you may feel during the fast. The level of discomfort felt from fasting varies from person to person and is nonexistent in many. Try out fasting and the various protocols to see if it’s right for you. Know that it takes about 2 weeks for your body to become accustomed to fasting regularly, and this discomfort will either diminish greatly or fade completely.

All variations of the same concept:

You will notice the above protocols suggest the exact same thing in that you limit your meals to a feeding window and dedicate the time outside of the window to fasting. The only difference is the amount of time spent fasting, and the length of your feeding window. Here is where you get to be flexible with IF and adapt it suit your lifestyle. Whether you prefer a 1x per week entire-day fast or a shortened daily fast what is most important is finding what works best for you and your lifestyle. Some people will do better with a shortened daily fast while others will prefer an extended fast for a single day each week.

It’s not necessary to be extremely strict with your feeding window and fasting time. That’s why it’s called flexible dieting. When I first learned of fasting and the 16-8 protocol I was extremely rigid with the time frames for the first couple months. Eventually I realized that this is unnecessary. If I am choosing to fast daily, one day may be for 16 hours with an 8 hour feeding window. The next day I may need to attend a breakfast with clients or family, and so I shorten my fast to 14 hours and extend my eating window to 10 hours.

I’ve become a fan of a 12 hour fast, where almost the entirety of the fast occurs during my sleep. For example eating my last meal at 10pm, sleeping from 12pm until 8am the next day, drinking coffee, and and breaking the fast at 10am. All I’m really doing is postponing my first meal by 2 hours, and I don’t even really feel like I am fasting. Read this article to understand why there is benefit in delaying your first meal by at least two hours after waking (as a warning though the article is very long and filled with scientific jargon).

Some weeks I may not follow a daily fast, and instead opt for the extended 24 hour fast at the end of the week on Sunday.

Do you see now how flexible this can be?

Looking at my own experience with IF as an example. Notice how I modify it to suit different goals. How long, and how frequently I fast depends mostly on my current training and body composition goals.

Weight Maintenance and Lean Bulking:

I’ve found that a 1x/week 24 hour fast is all that is really needed if I am only aiming to maintain my weight, or limit fat-gain while trying to bulk up and build muscle. I can eat at a surplus during the entire week with my training focused on progressing strength and building muscle and know that I will stay lean.

At the end of the week on an OFF-day such as Sunday, I fast from my last meal on Saturday until Sunday evening where I cook up a large meal that is very-high in protein (think 20oz NY strip steak with veggies + a casein shake), and resume my regular eating schedule the following day.  This is all that is needed to negate whatever surplus I created during the week, prevent fat gain, and maintain my current body fat percentage. It’s all about calorie balance over the long-term. I’m only concerned with what has happened over the big picture such as the entire month.I may include a 24 hour fast only once per month, and the other weeks it will only be a single 16-20 hour fast. Some weeks I may not even fast at all. Eventually it all becomes intuitive with enough practice.

Forget countless hours of steady state cardio. Forget meticulous calorie counting. Forget strict 100% clean eating. IF allows you keep things flexible, and still reach your goals.

A complicated process simplified:

You should understand that constantly throughout the day your body is storing and breaking down fat. Every time you feed your body stores fat. Some of the meal may be immediately broken down and used for energy. Some sent to the liver. Some sent to muscle cells. Some to your fat cells. It’s a continuous process of storage and breakdown throughout the entire day.

The majority of people think fat/weight gain is an immediate thing. You eat something calorie dense and ‘unhealthy,’ and that specific food is what caused you to gain an extra pound. False. The initial drastic increase in scale weight after a a high-carbohydrate day is more than likely water weight. Begin to look at the bigger picture over the span of a week, or better yet over the span of an entire month. You need to eat a surplus of 3500 calories to gain a pound of fat. To put that in perspective, that is a 500 calorie/day surplus over 7 days. If you’re exercising even semi-regularly it is not easy to eat the amount of food that is required to gain a pound of fat every week let alone in single day or weekend. More than likely you’re gaining fat pounds over the span of multiple weeks.

Example Month:

  • Week 1: +1500 cals
  • Week 2: -500 cals
  • Week 3: +500 cals
  • Week 4: +2000 cals
  • 1 month total energy surplus: +3500 cals = 1 pound of fat gained

This same concept can be applied to weight loss over a one month period.

Example Month:

  • Week 1: -2000 cals
  • Week 2: +1000 cals
  • Week 3: -1000 cals
  • Week 4: -500 cals
  • 1 month total energy deficit: -3500 cals = 1 pound of fat lost

If you go through the fall/holiday season of october, november, and december and gain 10 pounds of fat that means you have eaten a tremendous amount of food, and honestly have no clue as to what your energy needs are. See DIY: Calories and Macronutrients.

10 pounds of fat gained over 3 months would look like this:

  • 10 pounds of fat x 3500 calories/pound = 35000 calories
  • 35000 calories/12 weeks = a surplus of +2900 calories/week

That’s a surplus of +400 calories/day…which is really only like… 1 grande peppermint mocha latte from starbucks and a cookie every single day. I take that back, I guess it’s not that difficult to gain 10pounds over 3 months if you’re sedentary and rarely exercise. Hey! Here’s an idea: Exercise!

More Modifications: The Pure Bulk and Body Recomposition

In my own experience the 16-8 or 14-10 hour protocols are very effective when my goal is purely fat loss with strength/LBM maintenance. However, if your goal is purely weight/muscle gain I do not recommend a daily fasting protocol. It can become very difficult to consume enough calories to reach the surplus required for weight gain regularly. Trying to fit 3000-3500+ calories into 8 hours (usually 3 meals + a calorie dense PWO shake) is doable, yes, but not really fun for your digestive system.

The 16-8 protocol works very well for body recomposition, which is trying to slowly increase muscle tissue with a concurrent reduction in body fat. Whether or not the day is a training or off-day is usually what dictates whether or not I will fast. Body recomposition is accomplished by micro-cycling your calorie intake day by day by eating at a surplus on training days, and a deficit on non-training days. Fasting makes calorie/appetite control easier for when you’re strictly controlling and adjusting your intake day by day.

For example:

Training Day:

  • This is not an extended fasting day.
  • My goal on training days is to end the day in a surplus of energy.
  • I will postpone by first meal by no more than 2 hours after waking.
  • My calorie goal is divided between a small pre-workout meal, a post-workout shake, and 3 regular meals (lunch, dinner 1, and dinner 2).


  • This can be an extended fasting day.
  • My goal on non-training days is to end the day in an energy deficit.
  • The fast will be anywhere from 12-20 hours with a feeding window of 4-12 hours depending on how large of a deficit I am trying to create, and what my schedule is for that day.
  • My calorie goal is divided between 2-4 meals depending on the day, how I feel, my schedule, my desire to cook, and the deficit I am trying to create.

The posted links to,, and should provide any additional information you may want regarding fasting. The book “Eat Stop Eat” by Brad Pilon has now been revised and is available for purchase and download in e-book format. I recommend you purchase it if looking for more information.

Have specific questions from me on fasting? Feel free to comment or shoot me an email.

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