5 Reasons You should ALWAYS Workout During a Fast [Burn more fat]

5 Reasons You should ALWAYS Workout During a Fast [Burn more fat]

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5 Reasons You should ALWAYS Workout During a Fast [Burn more fat] – Thomas DeLauer

1) More Fat Loss

You’re exercising with your insulin and leptin levels at baseline, allowing for more fat burning to occur

Perfect study for this section is the intramyocellular lipids one, which shows the big difference between the two:

Study – The Journal of Physiology

During F but not during CHO, the exercise bout decreased IMTG content in type I fibres from roughly 18% to 6% area lipid staining


2) More sensitivity Post workout in order to build muscle

You can enhance this effect by working out fasted, which results in greater increases in p70s6k


Study – European Journal of Applied Physiology

Found: Increased p70s6k phosphorylation during intake of a protein–carb drink following resistance exercise in the fasted state – fasted training group saw a bigger increase in p70s6k


3) Get to take advantage of less fat cell sensitivity

Weight Lifting & Insulin

A study from the journal Diabetes found that strength training increases protein content of GLUT4, insulin receptor, protein kinase B-alpha/beta, glycogen synthase (GS), and GS total activity

Specifically, found that strength training for only 30 min three times per week is enough to see increases in insulin action in skeletal muscle


4) Cardio Increases Autophagy

It’s well known that fasting increases markers for autophagy (don’t yet have a direct way of measuring autophagy) and cardio boosts markers for autophagy as well

A study from the journal Autophagy found that exercise induces autophagy in peripheral tissues, such as muscle, liver, pancreas and adipose tissue, and in the brain



Fasting & BDNF

BDNF levels can be different in different places – you have blood BDNF levels, CSF BDNF levels (CSF is cerebrospinal fluid; a clear, colorless body fluid found in the brain and spinal cord) and BDNF levels in various brain locations

Fasting has been shown in many studies to increase BDNF – in fact, a study published in the Journal of Neurochemistry found that intermittent fasting increased the production of BDNF by 50 to 400%, depending on the brain region

Exercise & BDNF

Exercise induces neurogenesis, or the creation of new neurons – the new neurons are created in the hippocampus, the center of learning and memory in the brain

At a cellular level, it is possible that the mild stress generated by exercise stimulates an influx of calcium, which activates transcription factors in existing hippocampal neurons

The transcription factors initiate the expression of the BDNF (Brain-Derived Neurotrophic Factor) gene, creating BDNF proteins that act to promote neurogenesis

Thus the generation of BDNF is a protective response to stress, and BDNF acts not only to generate new neurons, but also to protect existing neurons and to promote synaptic plasticity

It has been shown that physically active people recover from mild depression more quickly, and physical activity is strongly correlated with good mental health as people age


it’s been shown that HIIT leads to greater increases in BDNF than LISS as it places more stress on the body:


A study published in the journal Medicine and Science in Sports and Exercise looked at the effects of HIIT vs LISS on BDNF levels in 15 volunteers

On separate days, two subsequent 30-min endurance rides were performed at 20% below the VTh (VTh – 20) and at 10% above the VTh (VTh + 10)

BDNF values increased from baseline after exercise at the VTh + 10 (13%) and the GXT (30%). There was no significant change in BDNF from baseline after the VTh – 20. Changes in BDNF did not correlate with VO2max during the GXT, but they did correlate with changes in lactate



  1. LJ Thompson on June 15, 2021 at 10:51 pm

    What if my ultimate goal is to lose weight asap

  2. Chase Potter on June 15, 2021 at 10:51 pm

    Question about the fat storage in the morning. Is that because of the circadian rhythm, and just because of the time of day? OR is “morning” implying when you wake up, whenever that may be?

  3. pinoskaya on June 15, 2021 at 10:55 pm

    please answer me on this! I fast 20 hours a day. I eat breakfast at 9 in the morning and then I have a reasonably large good meal at 12, then I fast until 9 in the morning after. I jump rope about 4 hours after I ate at 12 for about 40 min. is this wrong and dangerous?

  4. Gino dfs picks on June 15, 2021 at 10:55 pm

    Amazing video. Im literally witnessing the fat loss daily

  5. Chase Potter on June 15, 2021 at 10:55 pm

    So I guess our eating windows SHOULD be in the morning, huh?

  6. AbbyRavenclaw on June 15, 2021 at 10:55 pm

    how can i do that while avoiding fainting ?

  7. Zero TwoSixty on June 15, 2021 at 10:56 pm

    Should I drink a protein shake and not eat anything before workout ?

  8. Zero TwoSixty on June 15, 2021 at 10:56 pm

    I’m starting to see more veins and a vein is starting to be visible in my bicep. Am I losing fat ???

  9. JimmyV 5050 on June 15, 2021 at 10:58 pm

    I honestly take forever to digest food so eating an hour before my workout just makes me feel bloated and "burpy" during my training. Pour some pre workout on top of that and I feel like my stomach is swollen the whole time. Working out fasted is the only way for me 😁

  10. Christina Mason on June 15, 2021 at 11:01 pm

    It’s like fasting/workout calculus 🤯 Love these videos!

  11. trish b on June 15, 2021 at 11:01 pm

    butcher box is a lie!

  12. BotDood on June 15, 2021 at 11:03 pm

    wouldn’t you lose a lot of muscle mass?

  13. Javahar dumb on June 15, 2021 at 11:06 pm

    Grass fed is bull crap. Its like We all feed u best of foods and drinks so I and everyone may cut and hurt. You.

  14. Nicole Dumont on June 15, 2021 at 11:08 pm

    Any advice on this… I can do the fasting from the previous day (last meal around 5:30) and don’t have breakfast until 8 or 9 the next day… but can’t do exercise without something on my stomach, it starts to growl and I don’t do the exercises properly or with much energy

  15. Midnight on June 15, 2021 at 11:09 pm

    He says that fasting before your workout for MUSCLE GAIN and then eating afterwords is when you build more muscle. Not if you still workout specifically for muscle gain and then continue with fasting (let’s say an extended fast, 3-7 days whatever). So only do this if you are at the end of your fast OR, you are doing intermittent fasting specifically for muscle gain. Fat loss is totally different.

  16. R D on June 15, 2021 at 11:09 pm

    I have a question regarding fasted weight training. Aren’t our bodies in a catabolic state 30 mins or so upon waking up if we don’t eat? Doesn’t this burn muscle tissue? You say muscle have twice the absorption of nutrients during a fast, but wouldn’t it be counteracted by the burning of muscle tissue during the catabolic state? I’ve always done HIIT cardio fasted to burn extra fat, but I’ve always weight trained after eating since I thought my body was much more anabolic after eating. Look forward to your response!

  17. (browneverything) on June 15, 2021 at 11:10 pm

    what is fasting?

  18. John Glista on June 15, 2021 at 11:12 pm

    Been on keto for about 5 months now. I just cannot lift weights in a fasted state. Strength is always horrible and I struggle to make it through the entire workout. Even just eating 2-3 eggs as a meal before my morning workout makes a huge difference for me.

  19. Dixxi91 on June 15, 2021 at 11:14 pm

    I just woke up, I feel really inspired to workout right now in a fasted state. But I drank last night, so I won’t do that. I will give my body some time and nutrients to recover first. I used to feel fantastic when doing fasted workouts, I want to get back to that.

  20. Lukas Forsman on June 15, 2021 at 11:14 pm

    So lets say im starting my cutting season and try to get lean using this metod, should i still eat an ammount calories that sums up in a calorie deficit in a time period of 24 hours?

  21. Misty Lawrence on June 15, 2021 at 11:15 pm

    What happens to your muscles after?

  22. Sara on June 15, 2021 at 11:16 pm

    I get extremely fatigued on leg days if I go fasted, what should I do?

  23. Kehauna Kizzie on June 15, 2021 at 11:19 pm

    The thumbnail was misleading i thought I was clicking on to the gun show

  24. Sarah Long on June 15, 2021 at 11:20 pm

    How many hours after a meal would be considered fasting? Could I finish lunch at noon and consider my cardio after work (5ish) fasted? Or would I need more time?

  25. cole cole on June 15, 2021 at 11:21 pm

    Love this guy. Sometime I get lost in the science and the big words but that just b/c it’s new and I don’t understand them but I I admire his passion and trust him. Thomas my friend keep up the great work. It’s appropriate

  26. Tim Richards on June 15, 2021 at 11:22 pm

    So what if I exercise 18 hours into a 36 hour fast. 18 hours of no food after the workout. Is this good or bad?

  27. Joey Waite on June 15, 2021 at 11:23 pm

    Should I break my fast directly after working out?

  28. J Train on June 15, 2021 at 11:24 pm

    Awsome content, because of you I’ve lost 6.9 kilos since December 23rd ……it’s the 8th of February today……..and built muscle also…….can’t thank. You enough…..Hi from Australia 🇦🇺

  29. Jason Farmer on June 15, 2021 at 11:25 pm

    Thomas Delauer, my situation is I like to workout at 5am and my window to eat is not until 12/1pm (lunchtime) so I will not get to have a post workout meal or shake. How will that affect my gains as well as my IF set up? I want to make sure I am working this right, Thanks

  30. SilverPhantomX on June 15, 2021 at 11:25 pm

    I’ve been doing this for a few weeks and this is actually working after long intermittent fasting. The differences that I’ve known are, of course, loss of some belly fat and noticed parts of my muscles are gaining. Most of all, I’m able to surpass the belly fat and weight plateau for an entire week and this actually works. Thanks for this video and I really appreciate it!

  31. St.Fiacre on June 15, 2021 at 11:27 pm

    Light exercise on a fast is fine, but heavy powerlifting type shit drops the blood sugar too much, can feel like fainting.However, a day or two after the fast, brings extra strength with the added testosterone benefits, in my experience.

  32. wisdom4life on June 15, 2021 at 11:28 pm

    What we should realize is that our ancestors were active hunters and gatherers. They did not always have food to eat and during the dry seasons of the tropics and the winter seasons of the northern and southern regions of the world, there were days and weeks at a time when they had to go without food. In order to survive, they had to have the strength and mental clarity to hunt and gather to get food to survive. Those who could do it, survived. Those who couldn’t, died. We are the ancestors of those survivors and have their genes so we can function well during a fast.

  33. Stephen MacLeod on June 15, 2021 at 11:28 pm

    I just watched Jillian Michaels saying fasted workouts are a mistake. Listening to Jillian Michaels and taking her seriously is like taking Dave Ramsey seriously about advanced personal finance. 😂

    Brb, going for my fasted run… 😎

  34. Samuel Buckingham on June 15, 2021 at 11:32 pm

    3:05 – 3:18
    Muscel changes to Muscle on the white board lol

  35. Emile Kleinhans on June 15, 2021 at 11:34 pm

    Can I run in the morning fasted and only eat after work in the afternoon or should I have a post workout meal?

  36. NOthing mucH on June 15, 2021 at 11:34 pm

    Hey thomas, is it ideal to do a medium-high intensity run lasting from around 30-40 mins running around 7-10km in a fasted state? all i drink is a few cups of water before hand? thanks if u can reply ( ur fan from Hong Kong) thanks

  37. Deborah Salomon on June 15, 2021 at 11:37 pm

    I just experienced this and I’m so upset, went 3 weeks of training not fasted.. 😭 still lost a lot of inches but just now starting to lose weight.. smh

  38. Maester Gryphon on June 15, 2021 at 11:37 pm

    What if you fast for a month?

  39. Envertic on June 15, 2021 at 11:38 pm

    I always feel like ima pass out tho

  40. Thomas DeLauer on June 15, 2021 at 11:38 pm

    I appreciate everyone being here and taking the time to learn! Remember, the purpose of my content is to arm you all with the knowledge that you need to be the best version of yourself. It’s not a coaching system, it’s a pool of information!

  41. 335iTech on June 15, 2021 at 11:38 pm

    What if I don’t Have time to workout in the morning. I start work at 7am so I usually go after work.

  42. Jas on June 15, 2021 at 11:41 pm

    I just tried it for the first time and lost 700g in one day. Crazy!

  43. #ĀVREEEVANS on June 15, 2021 at 11:42 pm


  44. Rick Smith on June 15, 2021 at 11:42 pm

    I have been eating a lunch time meal, so really once a day…..then do a workout at around 6.30 in the evening after work ….then go to bed on an empty stomach and then do it again the next day. Will this work ok ? I always hear you should eat after a workout .
    Basically I eat in a four hour window and fast for 20 hours. Just wondering if this is effective?

  45. NoMxrcy on June 15, 2021 at 11:43 pm

    I workout daily, Ramadan is really helping me lose weight and my belly’s getting smaller I can also do 10 more pushups than normal

  46. Ru made on June 15, 2021 at 11:45 pm

    Yeah… I don’t agree with saying "if you eat before you workout you might as well not work out". Exercise of any kind has huge benefits for physical and mental health. If may not be the best path to get ripped, but it’s still better than sitting on your arse all day!

  47. Jessica on June 15, 2021 at 11:47 pm

    Love this guy!

  48. Jacob Wollam on June 15, 2021 at 11:48 pm

    This is awesome.

  49. Leo Joel on June 15, 2021 at 11:50 pm

    Our ancestors went hunting mostly on an empty stomach…..

  50. Matt Davis on June 15, 2021 at 11:50 pm

    I don’t know how, but I’m only on day two of intermittent fasting, and I’m saying words I forgot I knew. My brain feel so much clearer, and my workout was tough but I felt so good afterwards.