If a person with plenty of muscle & fat begins to go without food... (veggies, supplement)

[Zelpha]

...will the body begin to feed itself off the muscle first, or the fat first? Or both?

[ehealthguy]

The first day, the glycogen from the liver and muscles (roughly about 500 grams) is used.
Then the body starts to use fat as a source of calories, but also small amounts of proteins for various needs (many body molecules, such as parts of cell membranes and enzymes, are proteins).
When most of the fat is used, the body starts to use proteins from the muscles as a source of calories.

[schmedes2]

Short answer is both at the same time and the body burns more and more muscle as time progresses.

Why do you ask?

[Zelpha]

Originally Posted by schmedes2

Why do you ask?

Because I've worked hard to lose fat & build muscle and yesterday my bank account has gone into the negatives so I can't buy any food.

I don't want to lose muscle.

I gave the "plenty of muscle & fat" example as an extreme hypothetical so the point of my question would be clear.

Ehealthguy, thank you!

[tofur]

When fasting(i.e, no caloric intake of any kind), it takes around (I can't remember specifically) 30-48 hours before muscle breakdown starts to occur.

Your body starts stripping away muscle to supply protein for the repairing and maintenance of your organs (they wear out like any other machine), among other things. Keeping your vital organs healthy and functional is more important then muscle mass as far as your body is concerned. you can live without quite as much muscle mass, can't live without a functioning heart.

What happens as far as fat burning is concerned, is after 30 something hours your body starts burning intramuscular fat because the subcutaneous fat can't keep up with demand.

I don't recommend fasting for more then 18 hours a day. Do know though, that short term fasts like that don't destroy your muscle. Particularly when you've eaten protein before the fast. Our growth hormone levels go up ~2000% when fasted in order to preserve lean muscle mass.


If you are flat broke and are looking at some time spent in a heavy caloric deficit, I'd recommend that you make sure to get enough protein. Focus your food funds there to preserve lean mass. Think about getting some fish oil to supplement with, buy cheap veggies. But make sure your getting protein. And try to find a real cheap calcium supplement and take it daily.

But yeah, if nothing else just find the cheapest source of protein and veggies possible. You do have to eat eventually.

Also, do resistance training. It helps you retain your muscle mass. I wouldn't push too hard though since you won't be eating many calories.