September 20, 2011

Intermittent Fasting (IF)

Intermittent fasting is an approach to fat loss that supposedly enables you to shed bodyfat without necessarily reducing calories, or sacrificing strength and muscle gains, which is why it has gained popularity as an effective way of “dieting” in recent years. While fasting may sound somewhat unconventional by most standards, it can actually be a very effective way to promote your body to burn “stubborn bodyfat”.

Stubborn bodyfat generally refers to the most common areas that people have the hardest time getting lean. For men it is usually the lower torso (abs, erectors), and for women it is usually the thighs and butt. If you are a male and above 10% bodyfat, or a female and above 15% bodyfat, then stubborn bodyfat should not be your concern as it is likely that your overall bodyfat is too high to be focusing on getting “ripped”, as is.

Following a meal, insulin is released into the blood, the response varying based on the amount, as well as type of food (foods higher on the Glycemic Index will have the greatest response). Since insulin is a storing hormone, when present in the blood, the body is in storing mode and fat doesn’t get burned. As time goes by, and the nutrients are done being absorbed, insulin levels naturally begin to drop. The more time that passes, the more the body will start to burn fat at the expense of carbs. But how much time needs to pass? If you want your body to rely on fat as much as possible, literature suggests about 16 hours!

When insulin levels significantly drop with each passing hour after your last meal, the body senses an energy deficit and catecholamines (stress hormones – epinephrine and norepinephrine) are released into the blood. These hormones trigger fat mobilization. This is why intermittent fasting is as effective as it is at reducing stubborn bodyfat.

Like everything however, there is a point of diminishing returns. Since fasting is an effective way to prompt your body to burn fat, then in theory the longer you fasted, the more fat you’d burn. While this is somewhat accurate, it’s not necessarily the most effective way of developing your optimal body composition, as muscle would likely atrophy if you were to fast for too long. Literature suggests that you’re mainly burning bodyfat for anywhere between 14-20 hours after your last meal. After that point fat burning increases further but it is primarily intramuscular fat, not subcutaneous fat (which is the fat preventing you from seeing your abs!) as it cannot keep up with the demand.

Intermittent fasting calls for consuming your daily caloric intake within a fixed time frame (example, eat all your calories within an 8 hour feeding window). The rest of the time you are to basically live off of water, with the exception of BCAAs (or whey protein if you are on a budget) to prevent losing muscle.

The following are some guidelines to follow to maximize your results while intermittent fasting:

-          Fast should start when you go to sleep and last through the hours upon waking. The reason is because people have an easier time waking up and not eating, and no one likes going to bed hungry

-          Ideally you want to do your workout before eating, having only 10 grams of BCAA prior to training to prevent muscle wasting and maximize fat loss

Below are 3 blueprints of an intermittent fasting protocol. The difference between the 3 of them is what point in your day that you were to workout.

Blueprint #1 Fasted Training

6 AM – Wake up

Right before workout – Take 10 grams of BCAA

630 AM – Workout

Post workout (roughly 730 AM) – Take 10 grams of BCAA

2 hours later (roughly 930 AM) – Take 10 grams of BCAA

2 hours later (roughly 1130 AM) – First meal, should also be the largest meal of the day (high in complex carbs)

3 hours later (roughly 230 PM) – Second meal

4 hours later (roughly 630 PM) – Third meal, should also be the smallest meal of the day

*99% of calories should be ingested after the workout

**Protein synthesis climbs roughly 3-4 hours after training, and then peaks about 24 hours after, and returns to baseline 36-48 hours later

***Training in a fasted state should not lead to a decrease in performance, as there is fair amount of liver glycogen to maintain blood glucose (sugar) levels during training after an overnight fast

Blueprint #2 One Meal Before Training, Two Meals After

Pre-Workout Meal (Meat, vegetables and starchy carbs like potatoes)

Workout 2 hours later

Post-Workout Meal as soon as possible after workout, also the largest meal of the day (high in complex carbs)

Last Meal 4 hours later

*80% of calories should be ingested after the workout

Blueprint #3 Two Meals Before Training, One Meal After

First Meal

Second Meal 4 hours later


Third Meal Post-Workout, should also be largest meal of the day (high in complex carbs)

*60% of calories should be ingested after the workout

Important Points Of Consideration

-          No calories during the fast

-          Can have more than 3 meals during the feeding window, but most people prefer 3 for simplicity

-          Consistency is key, try to eat and train at the same times everyday

-          On rest days the first meal of the day should be the largest

-          On workout days, break the fast with meat and vegetables

-          Eat less calories on rest days by reducing carbs

-          Include a slow digesting protein in last meal to exert an anti-catabolic effect on muscle protein stores by ensuring your body has ample supply of amino acids until next meal, which would roughly be 16 hours away

-          Whole foods should always take priority over shakes

-          0.3-0.4 grams of carbs per pound of bodyweight in pre workout meal 1.5-2.5 hrs. before workout if you choose to use blueprint #2 or #3 (the amount is based on workout volume, higher volumes allow for more than 0.4 grams of carbs per pound of bodyweight)

-          This is not advised for those partaking in long endurance training

Training in a fasted state is ideal for fat loss, and getting shredded for a few reasons. Weight training activates enzymes and switches on genes that up regulates protein synthesis regardless of whether you are in a fasted state or not. However, when you provide the body with nutrients the exercise that is experienced is less of a stressor compared to training in a fasted state. Basically there is no need for the body to adapt or compensate when everything is provided to it. Because of this, literature suggests that there is increased anabolic activity seen post-workout as a compensatory response to the increased catabolism that occurs during fasted training. This can be summed up by thinking of taking one step backward, to take two steps forward.

Some literature also suggests that fasted training coupled with BCAA’s consumed pre-workout results in an elevated level of protein synthesis post-workout window. Protein synthesis is a metabolically costly process, which means ingesting BCAA pre-workout will boost metabolic rate for up to, or over 24 hours after a training session. On top of that, literature suggests that BCAA’s, or even just protein, consumed pre-workout will blunt cortisol throughout the day. As it relates to fat loss, lower cortisol may boost metabolic activity of muscle protein synthesis by allowing it to go unscathed (cortisol increases protein breakdown and decreases protein synthesis).

The most appealing factor to most, regarding intermittent fasting, is that when you do eat, you eat big. Dividing your daily caloric intake over 3 meals as opposed to eating 6 or more, spread throughout the day leaves you will a feeling of being “full” more so than if you had smaller portions. As far as frequent feedings (every 2-3 hours) needed to “stoke the metabolic fire”, well that has not been proven to be true. You cannot “trick” the body into burning more or less calories by manipulating meal frequency. At the end of the day, whether you had three 1,000 calorie meals, or six 500 calorie meals, you still finished with the same grand total of 3,000.

The only difference between relatively larger meals compared to smaller ones is that it just takes longer to digest. You still absorb all of the food you eat, it’s not like the body just dismisses it if there is too much. That goes for protein too. A common myth that exists is that you can only digest “X” amount of protein at a time, and the rest is wasted. Think about that for a second and look at it from an evolutionary standpoint. If we could only assimilate a relatively small amount of food at a time, is it likely that humans would have evolved to where we are today? Though it can only be assumed what prehistoric eating patterns were like, it’s not too farfetched to think that an average day consisted of waking up, and hunting early on to ensure that you would eat that day. If much of that relatively large meal was lost, or wasted, do you actually think humans would have stood the test of time and made it through thousands of years without food readily available like it is in the world we live in today?

Other common concerns with regards to fasting that should not deter you are:

1.    Hunger – Meal frequency is extremely individual. Some people may feel that fasting is not ideal and therefore this approach to getting shredded will not appeal to them at all. If you are thinking about being hungry, or believing the myths you have been told about needing to eat frequently, than guess what? YOU WILL BE HUNGRY! However, there is no literature to confirm that smaller frequent meals are superior to larger meals spread throughout the day for hunger and appetite control. If you are eating relatively large meals, as suggested with intermittent fasting, literature suggests that it takes up to 10 hours before your body is done absorbing all the nutrients, so it’s doubtful that hunger would play a deterring factor from continuing to abide by intermittent fasting protocols.

2.    Blood sugar – Blood sugar is extremely well-regulated and maintained within a tight range in healthy people. It does not swing up and down when you miss a meal. The thought of suffering severe hunger and mental impairment from not eating every 2-3 hours is ridiculous. Once again, look at it from an evolutionary perspective. Regular periods of fasting and/or famine were a natural part of our past, and we wouldn’t be here today if we were unable to function when obtaining food was most critical. Blood sugar is maintained within a normal range during a 48 hour fast, or severe calorie deprivation. Blood sugar would be identical after an hour and a half run whether you were in a fed state, or had been fasting for an entire day.

3.    Starvation mode – Skipping a meal or fasting for the better part of 24 hours does not equal starvation. Literature suggest that lowered metabolic rate in response to fasting is not impacted until 3-4 days have passed! Metabolic rate is actually increased during a short-term fast as the body ramps up levels of epinephrine and norepinephrine (adrenaline and noradrenaline) to sharpen our awareness and make us want to move around to find food to ensure we survive. Once again, this makes a lot of sense from an evolutionary perspective as this is a desirable trait that encouraged us to seek for food, or to hunt and kill, to prevent us from dying. If you were to fast for several days, then this survival response may have actually been counterproductive as an adaptation that conserved energy would have been advantageous.

4.    Muscle loss – Literature suggests that catabolism (muscle losing) only becomes an issue in prolonged fasting when stored liver glycogen becomes depleted. In order to maintain blood glucose, conversion of amino acids into glucose must occur. This happens gradually and if amino acids are not available from food, protein must be taken from the body in the form of muscle. Some studies have shown that muscle contributes roughly 50% to glucose maintenance after 16 hours, and it isn’t until 28 hours that it is nearly 100%. It is worth noting that muscle will only contribute to that degree when stored liver glycogen is fully depleted.

5.    Skipping breakfast and training in a fasted state – This is a rather debatable topic, as most people see breakfast as the most important meal of the day, due to repetitive studies that are published saying that people that eat breakfast have healthier body compositions than those that skip breakfast, and insulin sensitivity being at its highest upon waking. While insulin sensitivity may be relatively higher in the morning after an overnight fast due to modest liver glycogen depletion, if you strength train, you’ll have the same effect after your workout. Insulin sensitivity is increased in direct proportion to muscle glycogen depletion. The studies that are frequently published shining light onto the fact that breakfast is the most important meal of the day fail to highlight the fact that the “fatter” people normally associated with skipping breakfast, are the ones who lack the discipline to make the best decisions for their health. Whether these people ate breakfast or not, it is their lifestyle choices that result in undesirable amounts of bodyfat, not their meal patterns. Think, if you were to eat breakfast, and the food you chose to eat each morning was either a bagel, muffin, or leftover pizza from the night before, it wouldn’t make a difference what time you decided to have that.

6.    Fasting and cortisol – Ramadan fasting has been extensively studied, and none of the literature on it shows that short-term fasting has any effect on average cortisol levels. If Ramadan fasting, which is more extreme than intermittent fasting, has no effects, than intermittent fasting is just fine. Also, if Ramadan was to chronically elevate cortisol levels and leading to increased protein breakdown and depression, do you think people would still do it?

7.    Eating large meals at night – Once again, look to Ramadan fasting where nearly all of daily caloric intake takes place at night. Literature on Ramadan fasting shows that regular nightly feasts have a neutral or positive effect on body composition. Just like skipping breakfast is associated with higher bodyfat, late night eating is associated as well. Once again it’s worth pointing out that it’s the lifestyle choices that the people who eat late at night make, that influences their body composition, not that the clock shows a certain time.

How to practically apply an intermittent fasting protocol:

Your Basal Metabolic Rate first needs to be estimated, which can be done using the Harris-Benedict formula, as it is said to be the most accurate.

For MEN = 66 + (13.7 x weight in KG) + (5 x height in CM) – (6.8 x AGE)

For WOMEN = 655 + (9.6 x weight in KG) + (1.7 x height in CM) – (4.7 x AGE)

For demonstration purposes I’ll plug in my own metrics into the formula. At the time of this writing, I am 27, 170 CM, 82 KG

66 + (13.7 x 82) + (5 x 170) – (6.8 x 27) = 1,855.8

Multiply 1,855.8 by an activity level between 1.0 (sedentary) and 2.0 (professional athlete).

As a strength and conditioning coach, I’ll use a conservative 1.6.

1,855.8 x 1.6 = 2,969.28 is roughly how many calories I burn per day.

For fat loss you want to take in less than you are expending by no more than 20%. For demonstration purposes I’ll go with a conservative 10% less than my Basal Metabolic Rate.

90% of 2,969.28 = 2,672.352 is the required amount of calories needed per day.

2,672.352 / 3 meals = 890.784 calories per meal if you were to divide it up evenly (which is not ideal, but is easier to understand for demonstration purposes).

Next up is figuring out the macronutrient breakdown. Ideally you’d want to consume as many calories from protein as you do from carbs, 1 ½ grams per/lb of bodyweight being ideal in this example. That equals 270 grams of protein and carbs respectively, which equates to 1,080 calories from each macronutrient respectively. The grand total equaling 2,160 calories, leaving room for 512 additional calories by way of fat, or 57 grams.

Macro breakdown

40% calories from protein = 1,080

40% calories from carbs = 1,080

20% calories from fat = 512

Let’s plug these numbers into the fasted training protocol (Blueprint #1 above). Now as I said earlier, if the meals were divided evenly each meal would be roughly 891 calories. But since you want to taper from higher to lower calories, we need to calculate exact numbers for each meal.

We’ll divide the protein up evenly between all three meals, taper the carbs from high to low, and adjust the fat intake in direct proportion to carb intake. Specifically each meal will look like this:

Meal #1 = 40% of daily total = 1,069 calories

Carbs = 50% of daily total = 135 grams / 540 calories

Protein = 34% of daily total = 92 grams / 367 calories

Fat = 31% of daily total = 18 grams / 162 calories

Meal #2 = 30% of daily total = 802 calories

Carbs = 30% of daily total = 81 grams / 324 calories

Protein = 33% of daily total = 89 grams / 356 calories

Fat = 24% of daily total = 13 ½ grams / 121.5 calories

Meal #3 = 30% of daily total = 802 calories

Carbs = 20% of daily total = 54 grams / 216 calories

Protein = 33% of daily total = 89 grams / 356 calories

Fat = 45% of daily total = 25 ½ grams / 229.5 calories

Below is an example of Blueprint #2 and #3 that are listed above, in numerical order:

Blueprint #2

Meal #1 = 20% of daily total = 534 calories

Carbs = 20% of daily total = 54 grams / 216 calories

Protein = 20% of daily total = 54 grams / 216 calories

Fat = 20% of daily total = 11 grams / 102 calories

Meal #2 = 40% of daily total = 1,069 calories

Carbs = 40% of daily total = 108 grams / 432 calories

Protein = 40% of daily total = 108 grams / 432 calories

Fat = 40% of daily total = 22 ½ grams / 205 calories

Meal #3 = 40% of daily total = 1,069 calories

Carbs = 40% of daily total = 108 grams / 432 calories

Protein = 40% of daily total = 108 grams / 432 calories

Fat = 40% of daily total = 22 ½ grams / 205 calories

Blueprint #3

Meal #1 = 20% of daily total = 534 calories

Carbs = 22.5% of daily total = 61 grams / 244.5 calories

Protein = 22.5% of daily total = 61 grams / 244.5 calories

Fat = 9.5% of daily total = 5 grams / 45 calories

Meal #2 = 20% of daily total = 534 calories

Carbs = 22.5% of daily total = 61 grams / 244.5 calories

Protein = 22.5% of daily total = 61 grams / 244.5 calories

Fat = 9.5% of daily total = 5 grams / 45 calories

Meal #3 = 60% of daily total = 1,603 calories

Carbs = 55% of daily total = 148 ½ grams / 594 calories

Protein = 55% of daily total = 148 ½ grams / 594 calories

Fat = 81% of daily total = 46 grams / 415 calories

If you have any questions about intermittent fasting, feel free to contact me at I'm available for online consulting and personalized program design, as well as one on one training if you are located in the Greater Toronto Area (GTA).

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