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Intermittent Fasting

What are your current thoughts on intermittent fasting when trying to gain muscle?

I NEVER saw intermittent fasting as a good way to build muscle.

I did use intermittent fasting in my training career, even for up to 3 month periods. But they were never periods where I wanted to build muscle.

Heck one time I used intermittent fasting because I needed to get smaller!

I’ve used intermittent fasting to lose fat.

I’ve used intermittent fasting to lose size

I’ve used intermittent fasting to be able to eat what I wanted (not always eating shit) without gaining fat

I’ve used intermittent fasting to “program” a client to mobilize fat more easily.

But I never built significant amount of muscle mass or used IF with a client who wanted to build muscle.

I’m not saying that it’s not possible. I do think that about 20% of the population can gain muscle adequately on intermittent fasting. Those would be the cortisol under-producers. People who have almost zero anxiety, people who don’t get stressed about anything, those who have ice in their veins, those who are amazing under pressure.They can get away with IF and build muscle. Everybody else will either stay about the same (muscle wise) or lose muscle.

Among other things, cortisol is used to mobilize stored energy when you don’t have energy readily available (in your boodstream) because you ate not long ago. Cortisol also has the function of maintaining a stable blood sugar level. When blood sugar drops, cortisol is increased to mobilize stored glucose to raise blood sugar level.

There are 3 hormones and 1 neurotransmitters that primarily increase blood sugar level:

  • cortisol
  • glucagon
  • growth hormone
  • adrenalin

If you are some who is more naturally anxious, who worries a lot, don’t handle pressure well, etc. you will likey be a cortisol overproducer. During the fasting portion of the intermittent fasting approach these guys will release a lot more cortisol to maintain blood sugar levels (and mobilize fuel). Whereas the cortisol underproducers will release less cortisol and more growth hormone.

As you likely know, cortisol is catabolic: it can breakdown muscle tissue and also makes it harder to build new muscle.

Growth hormone can have an indirect anabolic effect by increasing the release of IGF-1, especially when insulin is also high. So with people who produce more GH during fasting, then train (which further increases GH) and eat their “feast” after the fast (which releases a lot of insulin) they get a big anabolic spike from IF which can help them build muscle.

So long story short if someone produces more cortisol (due to personality, lifestyle or job type) it will be pretty much impossible to build a significant amount of muscle with IF. And someone who produces low cortisol (due to personality, lifestyle, job) will be able to build muscle with IF.

As I mentioned, about 20% can build muscle with IF. These whould be the neurotype 1A and 1B personalities.

Type 2A can gain a small amount of muscle with IF while Type 2B and 3 will lose muscle on it.

Type 3 are also more likely to gain fat from IF. Why? because they have the highest cortisol levels of them all; it’s constantly elevated. Systemic cortisol elevation can decrease T3 (active thyroid hormone) by decreasing the T4 to T3 conversion. And it can also make you insulin resistant; both of which will make it harder to lose fat and easier to gain it.

But even for those 20% that can build muscle from IF, it is not the best approach at all to build muscle.

For 1A and 1B it can be okay to get lean.

For 2A it can be okay to get lean for 4-6 weeks

For 2B it can get them lean, but they will be bloated and have water retention issues

For 3 it’s to be avoided at all cost.


Coach your definition/preferences for “intermittent fasting”?

Warrior diet (snacking on veggies and protein all day then one big meal)?

24 hr fast twice a week? THen regular eating rest of week

Pulse feasting (mag 10 pulses followed by big meals)?

A 16/8 window, 18/6, 12/12 window?

A “fasted” training but using plazma? (So not really IF) first thing during the day? etc. etc.

lots of nuance & IF can be accomodated to fit lifestyle & neurotype?

it is really helpful for performance oriented careers, business builders etc…

I am writing an article on intermittent fasting, almost done.

As I just mentioned very few people can build an optimal amount of muscle on a “real” intermittent fast (14-16h fast, for more, and then 6-8 hours of eating daily).

I can get you lean IF you don’t overproduce cortisol.

I believe that only people with low cortisol (both because of neurotype, hormomal dominance and low stress life) should use a “real” intermittent fasting approach. So mostly type 1A and 1B with a low stress life. That is for optimal body comp results.

1A and 1B with a more stressful life (businessmen for example) CAN use IF to get leaner, but it won’t work well to build muscle.

2A can use it to get lean, but it won’t work that well to build muscle and normally they do better if they do IF for shorter periods (4-6 weeks).

2B and 3 should avoid real IF.

2B can use the MAG-10 pulse feast. And yes it needs to be MAG-10, amino acids won’t do. Why? First because MAG-10 has a complete spectrum of amino acids while BCAA and EAAs only have an imcomplete spectrum, which might work to stimulate anabolism but will not provide you the raw material to take advantage of that state. Furthermore BCAAs and EAAs which are right in leucine can trigger an insulin response, which is the last thing you want during a fasted period without any carbs in you body.

But the main reason why MAG-10 is superior for pulsing is the small amount of carbs in a servng as well as the type of carbs.

During a period of fasting blood glucose will go down, which is normal since you are using glucose for fuel (mostly by the brain but also body if you are active). This will lower blood sugar level and the body wants to stay at a normal level. So it will look to increase blood sugar to a normal level.

Four hormones/neurotransmitters can do that:

  • Cortisol
  • Glucagon
  • Growth hormone
  • Adrenalin

If someone is a cortisol overproduced he will use more cortisol to do that job. This is even more true if he or she is living a stressful life. This will make cortisol elevated throughout the whole fasting period. On the short term (during the fast itself) this can make you hold water, be flat and also put you in a catabolic state that will limit muscle growth. In the longer term this can lead to lower testosterone (or estrogen) levels, a reduction of he conversion of T4 into T3 (leading to a slower metabolic rate) among others. There is also evidence that chronically elevated cortisol increases the expression of myostatin, which will limit how much muscle you can build.

Not good!

Ok, back to MAG-10 . The small amount of highly branched cyclic dextrins in the product will allow you to maintain a stable blood sugar level during the “fasting” period and HBCD doesn’y spike insulin, especially not in doses of 5-10g so it will not lead to a rebound hypoglycemia.

If a type 2B or 3 (and even 2A) is dead set on using intermittent fasting then the only option I would recommend is the MAG-10 pulse fast. Even though it’s not intermittent fasting since nutrients are coming in during the whole day.

The 5/2 fating (two non-consecutive days of fasting per week) is not really what I would call intermittent fasting. It can work well both as a fat loss phase (allowing you to have less of a caloric restriction on the other 5 days) or muscle growth phase (to allow you to have more food on the 5 days while controlling fat gain on the other 2 days). I think it’s an extreme approach though. One could use the same pattern but have 3-4 doses of MAG-10 during the “2” days which will still give you a large caloric deficit but will also prevent most drawbacks.

The thing is that you need to be able to put these 2 days on low stress days and they have to be non-consecutive, which might be really hard to do for a businessman (to use your example).

I think that the biggest advantage of IF is that it is convenient and simple. For people who are super busy it can be appealing. But in the long run I don’t see it as more effective (if building muscle is among your goals), and for 60-80% of the population it will be less effective than a more traditional approach (for about 20% it will be completely counterproductive). I think that a lot of people are willing to sacrifice effectiveness for convenience and simplicity.


Beautiful thank you. One other thing that about IF (and what all the ravid followers love) is the mental clarity. BDNF spikes as does hgh/test (i know this latter is probably irrelevant).

But I say without a doubt that about an hour after waking, and some coffee and 4-5 hours into my “fast”…my focus, drive, mental clarity is OFF THE CHARTS.

I am scared to eat breakfast because I lose this “god mode”. It may be a high dopamine/adrenalane state (and possibly cortisol) but taht is OK as I am burning fat and just feel amazing.

I wonder if a mag10 pulse will allow me to feel this way while getting more muscle gain benefits. Or it may just be a pyscholocial re-wiring (convicing myself that mag-10/carbs during the day will not make me lose that laser focus/confdience/clarity)…

The best analogy i would make is look at the difference in effect brain candy has first thing in the morning on empty stomach/fasted state. Vs. brain candy after a heart breakfast of eggs, sausage, hash brown & toast. Day & night in terms of mental/mood productivity…

EDIT: It may be a pyschological/habitual thing but another good exmaple is during my fasted state, while drinking coffee… i can find something as boring as looking over financial statements and analzying tiny details EXCITING. If I have a big meal…i just want to watch youtube or consume entertainment. It’s that parasympathetic/sympathetic effect and is very real (at least for me)…

Sure, you can have more mental clarity when doing intermittent fasting. But not everybody feels it. And of course caffeine will have more of an effect when consumed on an empty stomach.

Listen, I know you are set on intermittent fasting, like you are on rings. But I personally cannot recommend intermittent fasting if your goal is optimizing body composition. But if you feel good on it, and you like the convenience, fine.

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I have tried IF, with an 8 hour window of eating from noon to 8 pm. It was okay after I got used to it, and would often get the “clarity and focus” after drinking coffee and getting past the initial hunger pangs.

In the long run, it didn’t match me or my personality type (I appear to be a 2b or 3 from CT’s explanations). The negatives for me:

  1. Jittery/anxious. I started to get a little shaky and would feel self conscious and that would make me more anxious.
  2. Obsessive. I would be strict in keeping this window, so I would overly watch the clock to be able to start eating.
  3. Strength. It was great for keeping lean, but not great for strength and performance gains.

I always looked at it more for the health benefits of helping lower blood pressure, giving the digestive system, pancreas, kidneys, etc a break and a chance to heal. However, I never feel energetic or “good” the times I’ve done it, most likely because as you mentioned of anxiety/stress.

But, I’ve always felt great the next day,
food feels like it’s getting put to good use and my stomach/bowel movements are great.

Curious though if you think there are those health benefits and if in the grand scheme of things it has a profound effect? I’ve only ever done this on off, non stress days

From your post I will assume that you are talking more about fasting a whole day or two in a week and the rest of the days are “normal” days. Rather than what is commonly seen as intermittent fasting (fasting for 16h or so and eating for 8 or so hours).

Regarding the health benefits, I’m honestly not sure about if those benefits are real or just belief/theory/wishful thinking with a 1-2 days per week true fast.

I know what they are probably not true for intermittent fasting because you are likely eating the same amount of food, but in a more compressed period. So even though your digestive system/kidney are not working as hard during the fast period, they are actually overloaded more during the feasting/eating period.

Yeah, 24hr fast, however I guess I figured the health benefits were still there during intermittent fasting but obviously what you mention makes perfect sense. I’m looking forward to the article, always have, always will love hearing your perspectives on these types of things.

Hi Coach

Just to clarify, do you believe the carbs as supplied in the MAG-10 would be sufficient enough to mitigate against increased cortisol production? As opposed, for example, to pulsing using hydrolysed casein/whey alone? Secondly, you have discussed elsewhere the use of cortisol controlling supplements, such as PPS, ashwaganda. Again, I assume this could be fed into such a protocol to further mitigate the cortisol affect from fasting and/or pulsing?

I think he mentioned carbs as being beneficial to avoid hypoglycemia from the leucine induced insulin release. I know that high leucine pure proteins can cause hypoglycemia, especially around activity.

Then again, low range blood sugar stimulates those counter-regulatory hormones. Mostly glucagon and adrenaline.

Personally I don’t think highly branched cyclic dextrin is much slower than glucose. Rice starch has virtually the same glycemic index as pure glucose. Mag-10 also has a second sugar Isomaltulose that is only split in the lower intestines which would provide a small blood sugar “tail” to negate rebound hypoglycemia. I think that is why it is included. Also a potential problem with hydrolyzed high leucine is a lack of electrolytes.

Valid points well made.

My reference to cortisol was in response to CT’s point about IF being unsuitable for Type 2Bs and 3s (of which category I consider myself falling into).

Not for muscle building and recomp. The main justification of IF is that it promotes autogaphy of abnormal and or precancerous cells.

A problem with high cortisol producers is that they can actually become more insulin resistant when fasting so I can see why IF might not work for them. Most people become very insulin sensitive after a 16 hour fast because muscle glycogen and ffas are depleted, clearing out room to slam in glucose easily.

I think that for a high cort producer, keeping muscle glycogen up would be necessary to minimize cortisol. The insulin from leucine may protect muscle but it won’t block cortisol and if glycogen depletion leads to cort induced insulin resistance then it can block GH too which can lead to chronic inflammation which just triggers more cortisol and then more insulin and less GH

I agree with the theory. Although it has been shown fat-adapted people can resynthesize glycogen almost as quickly as carb-fuelled folks so that shouldn’t be a huge issue. I have tested fasted glucose levels and they have always been in a good range, so I’m not concerned that IF is promoting insulin resistance.

Likewise, there is good evidence now that ketones are muscle-sparing. So, in addition to adequate protein intake, I believe I am covered there too.

The remaining question is whether keto dieters, especially those on low calorie diets, doing IF are more at risk from excessive cortisol production and the negative effects that can bring?

Anything that provides fuel is muscle sparing because it takes away the need to breakdown muscle tissue to produce energy.

Even if that were 100% true (it is never black or white) this is not applicable to intermittent fasting unless it uses a keto nutrients breakdown. Intermittent dieting is NOT a diet. It’s an eating pattern. It can be used with any type of nutrients ratio. If you keep a lot of carbs in you will not become “fat adapted” like someone who has been on pure keto for a while.

BTW I say that it’s not 100% true because even when I went on a low carbs/keto approach for a long time I still was flat, even when I was consuming a caloric surplus.

There is a difference between 1) increased fat burning on a fairly low carb diet (20-30%), 2) straddling the line of ketosis like Frank Zane for example recommended where he would drift in and out of ketosis but never fully adapt to using ketones as a prmary fuel source, and 3) being fully ketone adaped.

On fairly low carb diet, say 100-150 grams a day, glucose burning by muscles is down regulated. Muscle make fewer glycolytic enzyes and tend to load on fatty acids and will turn to them deeper into activity levels. From studies I had seen, athletes for example may burn 60% carbs at 6 mets on a 60% carb diet, but 40% carbs and 60% fat on a 30% carb diet. There is a mild physiological insulin resistance though because muscle cells are packed with FFAs which block entry of carbs. Also fat will be released from adipose more readily into the bloodstream which has a mild ability to disable circulating insulin (eating fat will raise basal insulin needs).
On a “straddling the line” diet where you may briefly shut off ketosis each day, tissues still burn glucose similarly to on a fairly low carb diet. The liver makes ketones, but the body is not very good at using them on demand As a result, a lot of energetic molecules (ketones) are excreted in sweat, urine and respiration. In a way, this is a method of getting your body to get rid of energy without having to burn it because the liver can not burn fat with 100% efficiency and the rest of the body does not give up on glucose as a fuel source. As a result, the body WILL make significant glucose via gluconeogenesis from body proteins because it is not getting enough dietary carbs to meet those needs, but it is not ready to use the ketones that the liver make.

When keto adapted, which may take 7 days or more of a full dive into ketosis, muscles use mostly fat and use ketones instead of glucose at higher workloads. Also the brain and nervous system and liver and some gut organs run on ketones. They stop using all but trace amounts of glucose and there is virtually no glycogen stored in muscles or liver at all. At this stage, because the body has replaced glucose burning with ketone burning, gluconeogenesis is significantly turned off and muscle tissue is not broken down much to supplement glucose demands Cortisol is turned down. So perhaps high cortisol producers could benefit from full ketosis.

While you could stay fully ketone adapted and use IF if you have enough body fat to provide FFAs and ketones, and probably keep glugoneogenesis turned down, IF in full ketosis kind of defeats the main purpose of IF which is to activate autophagy to destroy malformed cells and proteins in the body, since full ketonsis largely turns off gluconeogenesis. In other words, IFs main proported health benefit only works if you are “straddling” ketosis, not keto adapted.

And even if you are not fully straddling ketosis, IF users will often slip into ketosis near the end of IF, and will also crank up gluconeogenesis at the same time. This is why it can produce a slight rise in basal insulin needs. Ketones themselves cause mild insulin resistance much the same way that circulating triglycerides do.

Point is, IF and keto adapted state may work to reduce muscle wasting and burn fat, but its not “I.F.” for its supposed benefit of destroying precancerous cells.

Muscles never load on glycogen in a keto adapted state. They are almost entirely fat loaded and the body makes virtually no glucose. At that point it doesn’t even need glucose for the brain because the brain is using ketones. Also it does not reload on carbs very easily because muscles are fat loaded, and the pancreas does not respond very well to blood sugar rises coming off of a full ketosis state. Most people will fail a gllucose tolerance test coming off of ketosis, or even off of a 25% carb diet because muscles just aren’t using carbs, and circulating fat and ketones and counter regulatory hormones are turned up to make glucose from protein (in 25% state).

It is important to note that it depends largely on whether one is in ketosis or high fat burning state on a maintenance, or sub-maintenance calorie diet. Any time calories are sub-maintenance, muscles will deload on glycogen and or FFAs and THIS will raise insulin sensitivity, but insulin itself upregulated the production of glycolytic enzymes. When type 1 diabetics are diagnosed, they don’t just lack insulin, but their cells have completely shut off synthesis of glycolytic enzymes because they haven’t seen adequate insulin in such a long time. This is why early stages on insulin injection often kick a type 1 diabetic into temporary remission, because it turns back on glycolysis.

I know it came across as a circular argument but the reason I mentioned it is because some people, rather ignorantly, still claim ketogenic diets are catabolic in nature, i.e. because they result in gluconeogenesis, which is not strictly true.

Of course, Coach. The context was based on ketogenic dieting only. I should have made that clearer.