T Nation

Pre-Workout & Intermittent Fasting?


I read the article about screwing up intermittent fasting & all of it makes perfect sense, i have always been a fan of Warrior diet without any BCAA, but one thing i am still confused about is whether taking a pre workout would be counter productive or no? Mine consists of simple creatine, caffeine & 1-2 more compunds in very little amount (2-3gm), i know its not much, but i read somewhere that true fasting should only consists of water only, nothing else.


This has been answered in the respect that even a small dose of protein, especially something with a rich leucine content, is enough to halt the autophagy process in its tracks and switch you to more anabolic mode.

Warrior Diet creator Uri Hofmekler recommended you train fasted, for this purpose. Opposing this theory is more recent research from Brad Schoenfeld et al, which suggests training fasted is not such a good idea.

My take is you have several options:

  1. adjust your training time so you have a solid fasting period, followed by peri-WO nutrition and the workout itself;
  2. consider exogenous ketones (jury is out but there is some suggestion they do not impact on autophagy and may be muscle sparing in absence of protein);
  3. consider other stuff such as HMB and MCT/C8 oil: may impact on autophagy but at least won’t spike insulin;
  4. just train fasted and to hell with it (plenty of folks seem to be doing this).

I do a mixture of all 4 by way of experimentation, and as part of my current goal to ship 5-7 lbs. Of course, your training style will dictate matters. High volume routines will suck the more fasted you are. Low volume is much more manageable IMO.


Dude, HMB is completely worthless… good advice otherwise.


That’s what I did in my Warrior’s diet days. I would train at the end of the fast and start eating afterwards. Works good if your main goal is fat loss, can work if you are more concerned with strength (training fasted increase adrenaline levels) but not so much to maximize growth.

Now I time my fast so that it ends with the beginning of the workout and I have my peri to break the fast.


Cheers CT, I am a bit sceptical myself thanks to Jacob Wilson et al. That said, I can pick it up as cheap as chips so have been taking on faith with little to lose.


how about these ingredients?Any of these spike insulin?

Creatine Monohydrate–3 g
CarnoSyn® Beta-Alanine–1.75 g
Betaine Anhydrous–1.5 g
Taurine-1 g
L-Glycine-1 g
Caffeine Anhydrous-250 mg
Acetyl-L-Carnitine-250 mg


Are your daily calories in a deficit, at maintenance or in a surplus?


The glycine can activation mTOR (fasting is not just about preventing insulin, it’s mostly about not activating mTOR)


Deficit, i am consuming around 1500 mon-sat,& 2500 on Sunday, progress is there, lost around 5kg in last 6 weeks, i am 6’1 at 86kg currently


Thank you, no preworkout for me then.


Best way to do it. Break the fast with the periworkout (sipping starts on warmup/activation work). Sometimes I miss the 16/8 window doing this though (e.g finish eating 8 pm. Then morning workout around 8 am, seip plazma. Then lunch at noon etc)


I think that autophagy is more dependent on glucose availability than insulin levels. At under about 150 grams of carbs (25% maintenance cals) a day the body will turn up autophagy or start to increase turning dietary protein into glucose regardless of insulin levels. Basically, autophagy comes particularly when liver glycogen stores are on the low side but the brain is still functioning primarily on glucose. Autophagy is not significant in keto-adapted state because the brain no longer needs glucose at that point as it has plenty of ketones.

If you are eating a 500-1000 calorie deficit for several days with <150 grams of carbs, your body will be in autophagy, and also will turn some of your dietary protein into glucose.

I think that training with low insulin levels is fine for fat loss, while training with low glucose availability will kick up autophagy, but I do not think that daily autophagy is a good thing. It upregulates enzymes and pathways that turn protein into glucose. One 24 hour fast a week probably achieves the health benefits of autophagy regarding destruction of precancerous cells and old cells that have developed mal-shaped polypeptides that can be identified as antigens by the immune system.

Regarding fat burning, there was a contributor Lonnie Lowery who determined that rates of fat oxidation were not blocked by 1 serving of Mag-10 during morning training when compared to fasted training.

Is your goal to get autophagy or to keep fat burning up? Subjects who burn more glucose in training have been consistently found to burn more fat the rest of the day, and subjects who burn more fat in training have been shown to upregulate glucose/gluconeogenesis to provide energy the rest of the day.

Its an interesting subject and I am interested in the contributions of others on this thread but I think that a) fasted training; b) autophagy; c) ketosis (even mild transient prior to first meal of the day); and d) fat loss and recompositioning all get conflated. Fasted training may also increase GH release even during training that is not metabolically intense (walking and heavy, low rep weight training). Calorie restriction by 1000 a day is going to turn down and insulin, increase, autophagy, transient ketone production, and raise daily GH output regardless of timing IMO though I have to admit I will sometimes train for strength (with active rest periods) in a fasted state but I will always get in electrolytes and caffeine. For fasted electrolytes I usually eat 1-2 salt brined pickles plus brine.

Let me add that 5 grams of leucine only stimulates about as much insulin release as your body releases for BASAL needs in 1 hour in a fasted state. It is about as insulinogenic as glucose and your liver needs about that much insulin per hour to prevent an increase in glycolysis.


I’m not sure where you’re getting your facts and figures? My understanding is quite different. People who are keto-adapted can apparently trigger the autophagy switch with as little as a 12 hour fast; someone on a traditional western diet may need to fast way much longer. And where do you get a 24 hour fast once a week is optimum? For serious health improvement, reducing inflammation, addressing plaques on the brain, etc, that prescription will achieve diddly squat I’m afraid.


ketogenesis is in reality an alternate metabolic path from autophagy fueled gluconeogenesis. Generally, gluconeogenesis cranks up when carbs are below the needs of glucose dependent tissues (about 20-30% of BMR plus glucose burned in exercise). At this point there may be transient ketones after a night’s fast but the brain is still asking for glucose and fasting blood sugar usually rises to the 90’s as cortisol works to provide glucose. From what I understand, when the brain turns over to ketones instead, gluconeogenesis is virtually staunched and fasting blood sugar drops back to 70-85 range or even lower since ketones are displacing the need for glucose.

The original I.F. protocols I read 10+ years ago recommended I.F. Every second day, eating normally one day, then only eating dinner on the second. It also recommended only sliding into ketosis on that second day and maintaining 20-30% of basal calories from carbs so that Keto-adaptation would not staunch the need for a glucose source. Ketosis is a mechanism that metabolically displaces gluconeogenesis. On the other hand, very low carb diets with>15% of BMR from protein tend to result in fastin bag in the 90-110 range indicating to me that while
there is ketosis, there is not Keto-adaptation.

Keto adaptation may block cortisol by displacing the need for blood glucose, but cortisol is acutely anti-inflammatory. IF is anti-inflammatory by cortisol mechanism resulting in autophagy. To that extent, any spike in cortisol is going to cause autophagy and autophagy is a mechanism of muscle repair after training. It is the source of lymphatic buildup.

Granted, my understanding is incomplete and I’m trying to piece together what other’s are saying.


Here’s the thing. Low insulin can turn on autophagy by raising glucagon levels to provide glucose, but chronically low insulin levels greatly reduce the body’s use of glucose for fuel by downregulating glycolytic enzymes and replacing muscle glycogen with fatty acids. As a result, prolonged ketosis should eventually lead to glucagon dropping too, so that insulin and glucagon both end up low. Why would the body turn to autophagy when it has massively downregulated the use of glucose for fuel in prolonged ketosis? The cells have adapted to run without glucose.

At any rate, 30 minutes of walking causes significant autophagy. Turning to fat and ketones instead of glucose would obviously make that harder since there is a metabolic shift way from glucose utilization as a percentage of calories expended, and I see no reason why IF is any better than general caloric restriction plus exercise for activating the immune system to clean up bad cellular material.

The valid reason I see for fasted training is for fat burning (which is not halted by a serving of Mag-10 containing 5 grams of leucine and 11 grams of carbs anyway) and to promote GH and to increase post training insulin sensitivity.


Your point about cell adaptations supports the idea proper ketogenic lifestyles can combat cancer, i.e cancerous cells require glucose. Fasting should, in theory, further accelerate this process (see below).

In its simplist terms, autophagy will kick in when liver glycogen is depleted. Your description suggests this is neither required nor optimum. Yet, going back to the cancer example, or degenerative brain disease, even type 2 diabetes, this approach, I would argue, is not only sub-optimal but verging on a waste of time.

In terms of pure fat loss for aesthetic reasons, the above still stands. Fasting should, in theory, be as effective for a natural competitive bodybuilder as an obese housewife. I appreciate this is highly debateable, e.g Jeff Volek claims you start losing lean tissue in as little as a day; this rises until day 3, until it peaks and decreases thereafter. This translates as 5lbs after a 10-day fast in obese ‘healthy’ (emphasis mine) individuals. This seems counterintuitive from an evolutionary perspective and also from the fact GH is at a high level at such times. Personally, Volek’s claim are contrary to my own personal experience. And, from what I have read, from some physique-minded athletes, patently untrue.

It seems to me that despite studies in autophagy winning the Nobel prize in 2016, science is still behind the curve in accepting fasting as a bona fide weapon against modern lifestyle disease. Fitness and nutrition is also dragging its feet. Perhaps no one wants to prescribe a fast? After all, how much can you charge for that!!


Both Paul Carter and I have been doing fasting days every week. I have 2 fasting days and besides the body comp effect there I believe that there is a strong anti-aging effect as well as a myriad of others benefits from being in “AMPK” rather than “mTOR” mode.


Yes, I exchanged a few comments with Paul regarding that especially around the subject of exogenous ketones. You also pointed me in the direction of Joachim Bartoll; again a great insight into the subject - including dry fasting (haven’t tried that and don’t know if I plan to).

I’m toying with the idea of a future experiment which will involve going from circa 12% BF to circa 8% with aggressive fasting, e.g. within 30 days, without losing mass, and using DEXA (and possibly blood work) to document the journey. Perhaps after the festive period subject to finances.


Dear Christian,

Can you shed a light on how this revolves around certain stimuli? For instance; for me doing heavy lifting or steady state cardio in a fasted state gives me no troubles. Doing a CrossFit session during intermittent fasting (morning session) is an absolute no go! My body doesn’t wanna go and feels really burned out afterward. Could you perhaps give us some info on this through your blog/videos? The other ones on this topic have helped me out a lot! But sometimes a miss the connection to certain aspects of training and if intermittent fasting would be beneficial or not. Thanks!!!


Just a small point here for now. I have said nothing against the health and weight loss benefits of fasting. I have questioned whether I.F., and particularly fasted training produces added benefits on top a constant ketogenesis. Since Ketogenesis should virtually shut down growth of malignant cells by depriving them of glucose, then I am proposing that that makes IF on top of an extended state of ketosis redundant both for the “dieter” and for human physiology-that is to say that the body is not going to crank up autophagy when it is already blocking cell ageing and malignancy by another mechanism. IT’s also not going to turn up gluconeogenesis when it is fully adapted to run on fat and ketones. Likewise for I.F. for someone who is already on a 1000 calorie daily deficit and exercising. I.F. when I first read about it was proposed as a way to produce a period of a hypocaloric state for people who were not in a significant hypocaloric state over the course of a full 24 hours. The anti-ageing effects occur in a hypocaloric state whether there is an extended fasting period of not.

I.F. was not promoted as a strategy for people who are perpetually in ketosis. It was promoted as a way for people who were NOT perpetually in ketosis to simultneously go into ketosis and experience autophagy for a period of time 2-4 days a week. IT doesn’t make sense for someone perpetually in ketosis.