How much time can the human body stay without food

[George P Burdell]

Also, once the body starts burning fat, how long can you survive without food?

 

[eits]

you start making fats into carbohydrates after about 12 hrs of starvation, if i remember correctly.

 

[imported_bum]

Originally posted by: eits
you start making fats into carbohydrates after about 12 hrs of starvation, if i remember correctly.

When does starvation start?

 

[sswingle]

And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

 

[ViviTheMage]

Originally posted by: eits
you start making fats into carbohydrates after about 12 hrs of starvation, if i remember correctly.

I should try that, see how much I can lose starving myself...oh wait, no!

 

[sash1]

you burn muscle first

 

[inveterate]

Yo dude, diet and exercise is the way to go, DO NOT Starve urself, ONE it won't work, cuz thats just dumb. 2 you might end up eating more and giving up dieting all together. You don't need to EAT less to lose weight, all you have to do is RUN more.

 

[dxkj]

All the time? Daily? i dont get the question.

If you eat less than your body needs in a day, it digs into fat stores

 

[dxkj]

Also, dont drop below around 1200-1500 calories or your body will go into starvation mode and your metabolism will suck

 

[iamaelephant]

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

What makes you think this is a myth? I'm not trying to be disagreeable, it's just that every book and article I have ever read has touted this as a fact, and these are documents by people who know a lot about fat loss/management. Do you have a credible article that disagrees?

 

[BD2003]

Originally posted by: George P Burdell
Also, once the body starts burning fat, how long can you survive without food?

Different parts of your body run on sugar/fat. Your heat runs mainly on fat, and will keep pumping for quite some time. Your brain runs on sugar, as does primarily your muscles. In fact, you brain will start to eat away at your muscles for nutrition after a while.

You want to burn fat? Do cardio. Even slow cardio is fine. Get your heart pumping, if you want to burn fat. Lifting weights isn't going to do it.

But to answer your question, it depends on how much fat you have. If you have no food AND water, you've got a few days. A good supply of fat and water? A few weeks, but you will NOT be feeling very good.

 

[SludgeFactory]

Your body is running on a combo of fat and carbs throughout the day.

And the fatter you are, the higher percentage of fat (vs. muscle protein) you use for fuel during "starvation." There are cases of morbidly obese people being fasted under medical supervision for at least a year.

 

[dxkj]

Originally posted by: SludgeFactory


Your body is running on a combo of fat and carbs throughout the day.

And the fatter you are, the higher percentage of fat (vs. muscle protein) you use for fuel during "starvation." There are cases of morbidly obese people being fasted under medical supervision for at least a year.

by fasted you mean no food for a year?

links please?

 

[Legend]

I'm no expert, but I'd wager it's a combination of several variables that cannot be lumped into some blind X hours statement.

 

[eits]

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

it's not a myth... your metabolism alters itself to be slower because there's no need to go fast because there isn't any food to be metabolized.

 

[BD2003]

Originally posted by: eits

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

it's not a myth... your metabolism alters itself to be slower because there's no need to go fast because there isn't any food to be metabolized.

And on top of that, your body "assumes" you are going to be starving again eventually, and will make that extra effort to store a reserve of fat, just in case.

 

[iamaelephant]

Originally posted by: BD2003
You want to burn fat? Do cardio. Even slow cardio is fine. Get your heart pumping, if you want to burn fat. Lifting weights isn't going to do it.

[Cox] Wrong wrong wrong wrong, wrong wrong wrong <breath> Wrong wrong wrong wrong wrong! [/Cox]

If you want to lose fat permanently you need to build muscle. Muscle growth is the key to effective, healthy, long-lasting fat control. Cardio is important, but secondary.

 

[Injury]

Originally posted by: eits

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

it's not a myth... your metabolism alters itself to be slower because there's no need to go fast because there isn't any food to be metabolized.

Sounds sort of obvious when you put it that way.

Please correct me if I'm wrong:
As someone already mentioned, paying attention to your caloric intake is the most accurate way to burn fat. Fat stores calories, if your body is using less calories than you are taking in for a day, your body creates more fat cells to store the calories.

Muscles require calories to suppliment work. If you aren't using your muscles, they essentially die out because your body knows to not suppliment them if they aren't being used.

Fat cells that stay empty for a short period also die out.

What's the step I'm missing? If your body uses calories directly from fat, then wouldn't it make sense that staying active but not eating would burn calories very fast, while not doing anything and not eating would still burn calories at a constant, just not as fast?

 

[SludgeFactory]

Originally posted by: dxkj
by fasted you mean no food for a year?

links please?

It's referred to in the book "The Ketogenic Diet" by Lyle McDonald, I don't have the original source.

Think about a 500 lb'er with at least 300 excess lbs of fat hanging off their body. That's 1,050,000 calories of stored energy right there. At 4000 cal/day required to maintain that bulk, that gives them 262.5 days worth of energy, and that's assuming the 4000 cal/day stays constant throughout the process, which it doesn't since the caloric requirements gradually decrease as the person shrinks.

 

[ed21x]

Originally posted by: Injury

Originally posted by: eits

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

it's not a myth... your metabolism alters itself to be slower because there's no need to go fast because there isn't any food to be metabolized.

Sounds sort of obvious when you put it that way.

Please correct me if I'm wrong:
As someone already mentioned, paying attention to your caloric intake is the most accurate way to burn fat. Fat stores calories, if your body is using less calories than you are taking in for a day, your body creates more fat cells to store the calories.

Muscles require calories to suppliment work. If you aren't using your muscles, they essentially die out because your body knows to not suppliment them if they aren't being used.

Fat cells that stay empty for a short period also die out.

What's the step I'm missing? If your body uses calories directly from fat, then wouldn't it make sense that staying active but not eating would burn calories very fast, while not doing anything and not eating would still burn calories at a constant, just not as fast?

fat cells aren't typical cells... they are made for storage and do not die out.

 

[chambersc]

Originally posted by: dxkj
Also, dont drop below around 1200-1500 calories or your body will go into starvation mode and your metabolism will suck

That's basically my everyday and yet I have a high metabolism.

 

[TechnoPro]

Originally posted by: dxkj

Originally posted by: SludgeFactory


Your body is running on a combo of fat and carbs throughout the day.

And the fatter you are, the higher percentage of fat (vs. muscle protein) you use for fuel during "starvation." There are cases of morbidly obese people being fasted under medical supervision for at least a year.

by fasted you mean no food for a year?

links please?

Ultra-low calorie, vitamin-enriched shakes. So yes, in one sense, it is no "real" food. But they are given some essential sustenance.

 

[JEDI]

eat less and work out more. but dont quit the food intake alltogether.

ever since college, i've never eaten breakfast.

i would eat a small ham or turkey sandwich (wheat/rye bread) for lunch. then eat a plate of veggies for dinner.

i goto the gym for an hr (30 min cardio) 3x/week.

got my 6pack in 2 months doing this.

then the holidays came. over ate at thanxgiving. overate at xmas. drank waaaaay too much on new years.

then i moved and didnt join another gym.

 

[BD2003]

Originally posted by: iamaelephant

Originally posted by: BD2003
You want to burn fat? Do cardio. Even slow cardio is fine. Get your heart pumping, if you want to burn fat. Lifting weights isn't going to do it.

[Cox] Wrong wrong wrong wrong, wrong wrong wrong <breath> Wrong wrong wrong wrong wrong! [/Cox]

If you want to lose fat permanently you need to build muscle. Muscle growth is the key to effective, healthy, long-lasting fat control. Cardio is important, but secondary.

You are correct, but so am I.

Lean muscle mass burns calories constantly. Primarily in the form of glycogen, strings of glucose. In order for that fat to become glycogen, it has to be transformed in the liver. There is a limit as to how fast this can be done. Shouldn't have a problem recharging glycogen stores over time, so a higher amount of skeletal muscle will most definitely increase your body's energy usage over time - which is why its not a bad thing. Under rest and light excercise, skeletal muscles will also burn some fat, but nowhere near the rate the heart does.

Cardiac muscle on the other hand, is pretty much completely aerobic, and essentially runs on fat. You can push your muscles only so far before they go into an oxygen debt, and have to run mainly on glucose.

So when you're lifting weights, you're burning energy faster than you can restore it, and you're gonna have to stop and rest at some point. Do some cardio, pacing yourself, and you could go on for hours upon hours.

The rub in all of this is that your heart generally will only beat as fast as it needs to. Doing lots of cardio will get you a stronger heart, but not necessarily one which burns more fat. Skeletal muscles have to maintain a certain tone all of the time, so they're always burning energy.

So having muscle is certainly very, very helpful for maintaining a low weight. But if you're trying to actively *burn* fat, as fast and as efficiently as possible, without pushing yourself to exhaustion, light cardio is the way to do it.

 

[eits]

Originally posted by: ed21x

Originally posted by: Injury

Originally posted by: eits

Originally posted by: ScottSwingleComputers
And then there is also the myth that if you do this, once you eat something again, your body immediately stores it all away as fat in fear of being starved again, hence killing any gain.

it's not a myth... your metabolism alters itself to be slower because there's no need to go fast because there isn't any food to be metabolized.

Sounds sort of obvious when you put it that way.

Please correct me if I'm wrong:
As someone already mentioned, paying attention to your caloric intake is the most accurate way to burn fat. Fat stores calories, if your body is using less calories than you are taking in for a day, your body creates more fat cells to store the calories.

Muscles require calories to suppliment work. If you aren't using your muscles, they essentially die out because your body knows to not suppliment them if they aren't being used.

Fat cells that stay empty for a short period also die out.

What's the step I'm missing? If your body uses calories directly from fat, then wouldn't it make sense that staying active but not eating would burn calories very fast, while not doing anything and not eating would still burn calories at a constant, just not as fast?

fat cells aren't typical cells... they are made for storage and do not die out.

now, THAT'S a myth.

fat cells are storage cells, but they can be created and destroyed based on necessity. for some reason, some high school science teachers think that fat cells only grow in size and can't divide or die...