24 hour fasting and muscle loss?

[Mysterion27]

Hi guys! Iam due to have bloods taken soon and i will be required to fast for 24 hours beforehand! I never gave this any thought until now but when thinking about a 24 hour fast i first thought hmm i dont like the idea of no food for 24 hours but then i though well look on the bright side, iam gonna burn some fat ha

And thats exactly the question ... During a 24 hour fast,What is your body burning? Surely your body doesnt start breaking down muscle tissue during a 24 hour fast so iam assuming i would be burning fat? Although if thats true then why isnt 24hour fasting popular for fat loss?

So yeah, During a 24 hour fast, What is your body using for fuel?

[dmacdonal9]

I wouldn't say it's not popular, plenty of people do it. www.eatstopeat.com.

You're burning fat and stored glycogen. Muscle loss is not a concern in that short a timeframe (it takes more like 72 hours before you can measure actual lean tissue loss).

[Mysterion27]

I wouldn't say it's not popular, plenty of people do it. www.eatstopeat.com.

You're burning fat and stored glycogen. Muscle loss is not a concern in that short a timeframe (it takes more like 72 hours before you can measure actual lean tissue loss).

Thanks for the reply bud ;-) In theory so, wouldnt a 24 hour fast twice a week be great for burning fat and getting shredded? ha Not so sure ya would keep your sanity though haha

On a side note. When muscle does start to break down, At what rate does it breakdown? How much muscle would you lose in a week for example? I know it would vary depending on various factors but iam sure theres an average/ballpark figure? Seems kinda depressing that you could so easily lose the muscle you worked so hard to build so slowly

[Znik]

Thanks for the reply bud ;-) In theory so, wouldnt a 24 hour fast twice a week be great for burning fat and getting shredded? ha Not so sure ya would keep your sanity though haha

On a side note. When muscle does start to break down, At what rate does it breakdown? How much muscle would you lose in a week for example? I know it would vary depending on various factors but iam sure theres an average/ballpark figure? Seems kinda depressing that you could so easily lose the muscle you worked so hard to build so slowly

Considering you have to go 36+ hours just to get in a possible protein deficiency scenario, and like Dmac said more like 72 hours for any actual measurable lean tissue loss without eating. It's pretty hard to lose muscle unless you are starving yourself. With a reasonable diet and resistance training losing muscle is pretty hard to do and it does not happen easily.

[Mysterion27]

Considering you have to go 36+ hours just to get in a possible protein deficiency scenario, and like Dmac said more like 72 hours for any actual measurable lean tissue loss without eating. It's pretty hard to lose muscle unless you are starving yourself. With a reasonable diet and resistance training losing muscle is pretty hard to do and it does not happen easily.

So how come its so widely rumored that you lose muscle on a cut?

[stingray72]

I wouldn't say it's not popular, plenty of people do it. www.eatstopeat.com.

You're burning fat and stored glycogen. Muscle loss is not a concern in that short a timeframe (it takes more like 72 hours before you can measure actual lean tissue loss).

I agree.

[VinBin]

So how come its so widely rumored that you lose muscle on a cut?

You're confusing chronic energy deficiency (i.e running a cut) with the acute metabolic effects of a 24 hour fast. YOU WILL lose muscle on a cut, given that weight loss due to caloric restriction over time comes from both fat stores and muscle mass, you will never ONLY LOSE FAT on a cut.

The other scenario you're referring to is someone who is eating normally, and suddenly goes on a 24 hours fast, will first deplete acute energy stores, then glycogen, and then a mix of fat/protein for energy. Even in this 24 hour scenario there is energy from breaking down fatty acids and protein (just not significant amounts). While you may be in a negative protein balance at the end of the fast, there is no appreciable affect on muscle/lean body mass.

[Mysterion27]

You're confusing chronic energy deficiency (i.e running a cut) with the acute metabolic effects of a 24 hour fast. YOU WILL lose muscle on a cut, given that weight loss due to caloric restriction over time comes from both fat stores and muscle mass, you will never ONLY LOSE FAT on a cut.

The other scenario you're referring to is someone who is eating normally, and suddenly goes on a 24 hours fast, will first deplete acute energy stores, then glycogen, and then a mix of fat/protein for energy. Even in this 24 hour scenario there is energy from breaking down fatty acids and protein (just not significant amounts). While you may be in a negative protein balance at the end of the fast, there is no appreciable affect on muscle/lean body mass.

I understand what your saying! Basically theres a difference between one 24 hour fast and a consistent caloric deficit I was merely asking in relation to the comment above!

"It's pretty hard to lose muscle unless you are starving yourself. With a reasonable diet and resistance training losing muscle is pretty hard to do and it does not happen easily."

[Serpentarius]

So how come its so widely rumored that you lose muscle on a cut?

because people who do high reps and then go low carb (lol) deflate like a hot air balloon in the arctic tundra and lose all of their "strength" and think its muscle.

[Mysterion27]

because people who do high reps and then go low carb (lol) deflate like a hot air balloon in the arctic tundra and lose all of their "strength" and think its muscle.

Not to go off in a different tangent all together but i iam low carbing right now to cut weight and iam performing high reps depending on where iam at on my all pro's cycle but seem to be gaining strength

[Serpentarius]

Not to go off in a different tangent all together but i iam low carbing right now to cut weight and iam performing high reps depending on where iam at on my all pro's cycle but seem to be gaining strength

-being strong and experienced
-being a novice and making beginner gains

which one are you?

FWIW, low carb is completely unnecessary, especially for performance reasons. You will lose fat faster if you keep your carbs as high as possible.

[dmacdonal9]

So how come its so widely rumored that you lose muscle on a cut?

- Enhanced lifters stand to lose a lot when they cut, and they are the source of a lot of bodybuilding "knowledge".

- People don't understand the difference between lean body mass (which includes water) and actual muscle tissue.

- People overestimate their pre-cut LBM.

- When you're glycogen depleted you appear visually smaller and flatter, which people mistake for muscle loss.

- Training intensity drops, so people think they lost muscle.

[Perfect1O]

Although if thats true then why isnt 24hour fasting popular for fat loss?

It IS effective for fat loss. You're burning fat. The main reason it's not more popular is because people aren't comfortable with it. They don't WANT to go an entire day with no food. Personally, I don't like eating at a deficit every day. I enjoy my fasting days. I feel I get a lot done and have plenty of energy. For this reason, I've started fasting 2 days/wk instead of just one, with the benefit of not needing to track my calories as carefully on the other 5 days.

Many people share a different experience of fasting: That of being hungry/tired/irritable and so on. Why would they voluntarily put themselves through that? When I talk to people about doing a day-long fast their response 90% of the time is "damn dude I couldn't go a whole day not eating anything". That's the reason. It's not going to hurt you.

[ironmaniac508]

-being strong and experienced
-being a novice and making beginner gains

which one are you?

FWIW, low carb is completely unnecessary, especially for performance reasons. You will lose fat faster if you keep your carbs as high as possible.

This, also people overestimate how much protein they need...carbs are muscle sparing and keep your performance up both in the bedroom and the gym/track/ring etc. Please dont fall into that ketogenic nonsense.

The lbm loss a lot of people say that happens during a cut is really just glycogen depletion, glycogen draws water into your muscles...so basically when you are depleted your muscles are flat from being dehydrated. A lot of low carb fad type diets are so main stream because people see how quick they lose "weight" when very little of it is fat. Everyone wants a quick fix these days, no one wants to work hard or put the time in to see results.

[Ruben777]

I am into competing in natural bodybuilding competitions, but I also like to do a prolonged 24 hour fast every week year round (offseason and onseason). Is that advisable for competition bodybuilding?

[SuffolkPunch]

It's probably OK if you were eating plenty the day before - but if you've already spent time in a deficit, it might not be.

Bear in mind that the guy who popularised IF, Martin Berkhan suggests that males should never fast for more than 16 hours.

There is also evidence that it's optimal to have 3-5 widely spaced protein feedings per day for muscle growth (and that extends to muscle preservation during a diet).