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Fasted Training vs Eating Before Workouts: Study Compares the Difference – Thomas DeLauer

This is the official fasted training versus non-fasted training video. What I mean by that is we’re going to look at some of the science between what happens when you train in a completely fasted state, whether it’s overnight or after an intermittent fast, or if you’re training after eating some food.

It’s a common battle that’s occurring on the internet. It’s a common battle that people talk about all the time. Which is better? You get a little bit more power when you’re training with a little bit more energy in your system, but you might get a better response if you’re training in a fasted state. So let’s look at the science, and there’s one particular study that I want to reference that’s going to break it all down and give us some clear cut answers.

But the first thing that I want to talk about before we go into any detail on anything is I want you to stop worrying about if you’re going to lose muscle or not. Here’s the thing, if you work out for long enough, if you work out for long periods of time, yeah, you’re going to burn up some muscle, but if you’re training in a fasted state, the last thing I want you to worry about is losing muscle. Whether you’re a man or woman, it doesn’t matter. You’re not going to lose as much muscle as you think, if any. The fact is you have way too many hormones that are skyrocketing when you’re in a fasted state that far supersede the effects of catabolizing muscle.

You have high amounts of human growth hormone that stop the breakdown of muscle. Okay? But the other thing is once you’ve been fasted for a longer period of time, your liver starts to produce something known as BHB, Beta-Hydroxybutyrate, which is a ketone body. That ketone body stops what is called leucine breakdown or leucine oxidation. Leucine is an amino acid, and that amino acid is at the forefront of catabolism, muscle breakdown. It’s very simple. If we have leucine in the equation, you’re not breaking down muscle. If leucine is oxidizing, you’re breaking down muscle.

In the case of fasting, when you have ketones present from a fast, it doesn’t mean you have to be in ketosis, it just means you’ve been fasted, you have enough of this overall ketone production to make it so that you’re not going to burn up that muscle, and you’re not going to go into that leucine oxidation.

So now that that’s out of the way, let’s truly talk about the difference between training fasted and training fed, and there’s one study in particular that really took a good look at this. It was published in the Journal of Physiology, and it took a look at something entirely different from what we’re used to seeing.

You see, normally the argument for fasted cardio is really simple. It’s kind of bro science, but it kind of makes sense at the same time. People will say that fasted cardio is good simply because you’re burning through all of your glycogen. Glycogen is your stored carbohydrates in your muscle. So they say that because you’re training in a fasted state, you burn through that glycogen, and your body has no choice but to start burning fat because you’ve already gone through the glycogen. That’s a simple theory, and it kind of makes sense, but it’s not the truth. That’s not why fasted cardio is better. That’s not how it works.

So what this study looked at is it looked at something known as intramyocellular lipids. You see inside of our muscles, we have little itty bitty, teeny, tiny bits of fat.


1) Muller AF , et al. (n.d.). Ghrelin drives GH secretion during fasting in man. – PubMed – NCBI. Retrieved from

2) Nørrelund H , et al. (n.d.). The protein-retaining effects of growth hormone during fasting involve inhibition of muscle-protein breakdown. – PubMed – NCBI. Retrieved from

3) Pan JW , et al. (n.d.). Human brain beta-hydroxybutyrate and lactate increase in fasting-induced ketosis. – PubMed – NCBI. Retrieved from

4) Very-low-carbohydrate diets and preservation of muscle mass. (n.d.). Retrieved from

5) Exercise in the fasted state facilitates fibre type-specific intramyocellular lipid breakdown and stimulates glycogen resynthesis in humans. (15, April). Retrieved from

6) Hormone-sensitive lipase – an overview | ScienceDirect Topics. (n.d.). Retrieved from


  • Weee Van

    Posted July 21, 2021 10:25 am

    Working out on an empty stomach is best but dont over do it or you may have mental foggyness. (At least in my case)
    Then I eat a nutritious shake, blended with cacao, almond milk, acai powder, collagen, a mix of cruciferos vegetables in powder, vanilla extrac, and stevia. Along with 4 over easy eggs on top of an avocado and occasional toast with keto dark chocolate almond butter.

  • nelson israel

    Posted July 21, 2021 10:25 am

    What happens when you eat immediately aftet a work out. With different types of food

  • shahad Nashi

    Posted July 21, 2021 10:25 am

    I usually do hitt workout when I’m fasted , after this I start lifting weights when I’m fasting and tbh much better energy & the results just in 10 days much different , i only do 20-15 min of workout yes I’m a new pie 🥧

  • thelox2020

    Posted July 21, 2021 10:25 am

    Moral of the story train fasted ….

  • Eric Carr

    Posted July 21, 2021 10:25 am

    I love how smart this dude sounds

  • Ha Hoang

    Posted July 21, 2021 10:25 am

    Way toooooo much info!!

  • Big Boss

    Posted July 21, 2021 10:25 am

    In ramdan i used to be fasted for about 16 hour , when i workout at the end of fasting period surprisingly ia got greater performance and strength than in the full stomach situation .

  • Rick Weide

    Posted July 21, 2021 10:25 am

    How long should I be fasting before a workout? Are we talking about 4-6h? or 8-12h? Can anyone help?

  • Jesse Morales

    Posted July 21, 2021 10:25 am

    Should I eat a load of protein right after or wait ! Right now I’m eating in that window of 30 mins after my workout!

  • Albert Hachfeld

    Posted July 21, 2021 10:25 am

    Great insight, thanks man!

  • Asheesh Verma

    Posted July 21, 2021 10:25 am

    Great information.

  • The 4 Horsemen

    Posted July 21, 2021 10:25 am

    Utilizing coconut oil while fasting improves the ketogenic response and speeds it up. Coconut oil also is a direct source of energy for the liver which is what's responsible for helping release ketones.

  • Monte Hammon

    Posted July 21, 2021 10:25 am

    You can't just take belly fat and put it in your muscle

  • Life Is War God Is All

    Posted July 21, 2021 10:25 am

    Fasting is faster! Thanks bro.

  • Frozen Europe

    Posted July 21, 2021 10:25 am

    Video coudve been one minute long

  • gqganey

    Posted July 21, 2021 10:25 am

    150 grams of carbs? What if it were only 20 grams of carbs.

  • wad

    Posted July 21, 2021 10:25 am

    The bit on belly fat seems weird to me. Isnt spot reduction a myth?

  • Ugly Fucking Bastard

    Posted July 21, 2021 10:25 am

    Very clear and informative!

  • Galih Candra

    Posted July 21, 2021 10:25 am

    What's with the thumbnail? Flexing your garage? I didn't see rented lambo or ferrary.

  • B1ack_Raven

    Posted July 21, 2021 10:25 am

    How long should you wait to feed after a fasted workout?

  • Harry Georgiou

    Posted July 21, 2021 10:25 am

    Has a video been done on the percentage of muscle mass gained in the two states?

  • tk

    Posted July 21, 2021 10:25 am

    I'm long and skinny so does this video fit me?? Expert opinion plz

  • Pierson Cook

    Posted July 21, 2021 10:25 am

    I dont think it's possible for one to decide what part of your body will burn fat.

  • Adrian JF

    Posted July 21, 2021 10:25 am

    100% true🙌🙌🙌 I started doing IF and not eating 5 meals as I used to. Doing fasted(16hours) workout and the pumps are awesome. And only 3 meals. Lost most fat and kept muscle. Feeling amazing and energetic now that I know every time you eat your insulin level goes up in the blood, just hit your protein, healthy fats, and low carbs and you’re good to go

  • Dustin Hetrick

    Posted July 21, 2021 10:25 am

    I've been lifting for 14 years doing the 6+ meals/day thing. About a year or so ago I found Thomas Delauer and took some of your advice. I do a 16/8 (sometimes 17 or 18) and lift fasted mid day, then eat my 3 meals up until 8 or 9pm. I'm now considering doing 2 meals/day. I've considered OMAD, but not sure how I can eat 3,000k calories in one sitting! Although I've learned I feel much better when fasting versus being in a fed state.

  • Bender c777

    Posted July 21, 2021 10:25 am

    The ultimate douche canoe flex is having a chevy nova in the thumb nail lol
    You fitness gurus are all the same, just a bunch of paid actors to pitch bs fitness program

  • Jonathan Hadley

    Posted July 21, 2021 10:25 am

    Would it better to consume some food b4 doing some exercise (small!) if you've got damaged Mitochondria ie C.F.S Rather than try doing some exercise (small!) fasted? T.I.A

  • Khaled Hasan Shagor

    Posted July 21, 2021 10:25 am

    I do fasted weight lifting in tbe morning then 20mins cardio after that. Is that good?

  • D S

    Posted July 21, 2021 10:25 am

    Worst use of cutaways of all time. what the hell is the point of this crap?

  • Carlis Flores

    Posted July 21, 2021 10:25 am

    Just excersise in the morning then eat

  • playzone

    Posted July 21, 2021 10:25 am


  • Jonny Carroll

    Posted July 21, 2021 10:25 am

    Good for the average natty joe trying to put a bit muscle on and keep body fat down. Not optimal if your serious about bulking. Im sure Mr Tren’DeLauer didn’t get that way from just fasting alone 🤣

  • lucasdcurcio

    Posted July 21, 2021 10:25 am


  • amt1045

    Posted July 21, 2021 10:25 am

    Please share how a night only fasted early routine should look like… specially for women. Something like….wake up, stretch, start exercising, drink bla bla during exercise and eat bla bla after exercising xx minutes after finishing your workout. Thanks

  • C Jay

    Posted July 21, 2021 10:25 am

    If you're doing bench press on a smith machine with only 50%, range of motion then just don't worry about training at all

  • Brandon Villatuya

    Posted July 21, 2021 10:25 am

    3:34 which sounds very painful
    *And IS very painful*

  • Cap G

    Posted July 21, 2021 10:25 am

    I don't care about the science behind it… just tell me what YOU do like jeez

  • chon rodriguez

    Posted July 21, 2021 10:25 am

    I been doing fasted workouts for.a while now I have alot of water when I wake up than have a couple of blueberries than some coffee than some honey and than go like a maniac at the gym im there for like 2 hours i can't enough. I feel like I need to eat alot more though like I'm losing to much muscle starting to feel like I'm training for a fight when I'm really trying to get shredded if that makes sense

  • Dragon Negro

    Posted July 21, 2021 10:25 am

    As long muscle isnt broken down during fasted training I'll keep doing it

  • Steve White horse.

    Posted July 21, 2021 10:25 am

    Thomas 💪🏼 Never knowingly explained something in 1 minute, when he can explain it in 8mins. 🤣👍🏻
    Me i just gotta have a shake, or egg white omelette before training, I've noticed my performance is 15% worse, wirhout something inside.

  • Claudius Stammbach

    Posted July 21, 2021 10:25 am

    How about exercising (heavy lifting) after having been on a fast for over 40 hours? Would you still recommend not eating before?

  • Judd Otto

    Posted July 21, 2021 10:25 am

    Feel much stronger and better endurance when fasted

  • Sergio Mcfly

    Posted July 21, 2021 10:25 am

    Nothing compares to a good sleep night prior to workout, absolutely NOTHING, even food

  • Adam Richardson

    Posted July 21, 2021 10:25 am

    So he’s essentially paraphrased the bro science?!🤔

  • Steph S

    Posted July 21, 2021 10:25 am

    Fasted training OR Tom DeLauer training faster after a month of 50mg daily Anavar…!

  • CV

    Posted July 21, 2021 10:25 am

    Can you clarify if this only applies to fasted cardio. From what i'm seeing in the studies this only looked act cardio based training. Not heavy Weightlifting.

  • Kainthemain

    Posted July 21, 2021 10:25 am

    if you wanna build most amount of muscle, dont train fasted. If you just wanna be healthy you can train fasted. Its not really rocket science.

  • Rich Burmond

    Posted July 21, 2021 10:25 am

    Did someone say Human Growth Hormone ??? :))))

  • 0527MK

    Posted July 21, 2021 10:25 am

    I feel sluggish if I don’t eat anything but pre workout and water during before workout

  • danermanerkider

    Posted July 21, 2021 10:25 am


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