How quickly does a body start to catabolize muscle?

[jp1957]

Most of the time I'm running at a 20% deficit , with an occasional day of even 50%.(working on only losing 2-3pds per month, to not lose much muscle)

I was reading an article recently touting an occasional fast day.

My question though as above, is how quickly on a fast type day, does the body begin to burn muscle?

 

[SdBronco]

You will get lots of opinions on this. Most will be bioscience but there are plenty of people who fast with great results. It really depends on your nutrition not how long you go without eating but at the same time i wouldnt be looking to do any fasts over 18+ hours (16 is considered conservative for fasting) and i also wouldn't workout in a fasted state unless i was breaking my fast with a post workout meal or a shake.

 

[jp1957]

In reality, for me its not really a fast, rather a significantly lowered calorie count for the day. I usually need to eat every 3 hours. When getting bloods, 12 hours is a killer. I couldnt imagine 16 or greater.

 

[RickRock]

Most of the time I'm running at a 20% deficit , with an occasional day of even 50%.(working on only losing 2-3pds per month, to not lose much muscle)

I was reading an article recently touting an occasional fast day.

My question though as above, is how quickly on a fast type day, does the body begin to burn muscle?

Fasting for one day isn't really going to catabolize anything assuming you have adequate macros on other days. It's the continuous excessive defecits that causes the Catabolism. ADF (alternate day fasting) has been shown to be a pretty effective dieting tool for many that have implemented it correctly. Not only do many maintain their mass and strength but I've seen gains made on it as well.

 

[olderbro]

What is your current bf%? Until you're pretty lean the body won't lose much muscle on a calorie deficit.

 

[jp1957]

Right now I'm still a fat ass. But about 1/2 way there now.

 

[jp1957]

But to the point, I want to make sure I lose the minimal of muscle I can, which is why I'm doing only a 20% defcit, but there are occassional days (like a day day for example) when I eat almost nothing all day. Or other occasional days I might be at like a 50% deficit. But never a complete fast. Nothing longer than prob 12 hours.

 

[RickRock]

But to the point, I want to make sure I lose the minimal of muscle I can, which is why I'm doing only a 20% defcit, but there are occassional days (like a day day for example) when I eat almost nothing all day. Or other occasional days I might be at like a 50% deficit. But never a complete fast. Nothing longer than prob 12 hours.

As long as it's not too regular I don't see a huge issue. I'd just try to maintain what consistency you can day to day. Judge things based on measurements, the mirror, and gym performance and you'll know if you are headed in the right direction

 

[jp1957]

I lift 2-3 days a week cardio 4-5 days a week. Just depends how I feel if I take a day off or not.