To those of you who have lost weight - I am at a loss - I just can't fathom it coming off me. How does it come off? Where? Through what?

Not only can I not imagine where the fat will dissapear to (or I guess the cells shrink) - but where does it go when it dissapears - all mass exists still in the world somewhere

so sweat, poop, fuel - which then comes out as sweat?

heeh - I just can't imagine the extra pounds leaving easily - They never have.

does my question even make sense?

this is unbelievable! i was thinking the exact same thing this afternoon

at first i thought, perhaps it could be said that the fat/weight is lost through excretion but then i thought perhaps it is absorbed into the body - say the muscles? it still doesn't equate to where the "mass" went.

very interested in the scientific answer.

A calorie is actually a unit of heat. Fat is fuel, you burn it off as energy. Like the fuel in your gas tank or the oil in your furnace
Sweat is water with a bit of salt etc in it.
Excrement (poop) is fiber and undigestible stuff you eat.
The nutrients in your food are what make new cells, like skin cells that slough or new heart cells ....

yes but fuel comes out as exuast as well. hense....
is the fat turned into something?
Yes I understand it is energy, but how - and I thought you burned by breaking up - maybe that is what I was wondering

some info from the web - by no ways complete

3) When I lose weight, is the mass burned for fuel, and if not, what
happens to it?

If, by "mass" you mean the mass of the food, Yes, because we are
talking about a calorie, a unit of heat or energy. When you lose
weight it is because you have expended more energy than you consumed.
This means that you have not only burned off all the food you just ate
(by building muscle and running other bodily functions), you also drew
from your reserves (fat). So yes, you "fuelled" your body with the
mass you consumed.

If you are talking about the mass of the fat we burn, the answer is
still Yes. Our bodies "burn" calories through metabolic processes, by
which enzymes break the carbohydrates (starches) into glucose and
other sugars, the fats into glycerol and fatty acids and the proteins
into amino acids.

These molecules are then transported through the bloodstream to the
cells, where they are either absorbed for immediate use or sent on to
the final stage of metabolism in which they are reacted with oxygen to
release their stored energy.

It helps here to understand the concept of the calorie ----

Often the misconceptions about weight gain (and loss) are a result of
people not understanding what we mean by a "calorie". They often think
a calorie is a little "thing" that has to be gotten rid of. A
calorie is a unit of energy (or heat). For food it defines how much
energy is needed to burn of a unit measure of a particular food. For
exercise it means how much energy your body is burning. So all this
means is that the more calories a food *has* the more energy it takes
to burn it up.

anyway I should go to bed - I am done "burning" for the day...

The fat is "burned" (like in a petrol engine) turned into kinetic energy (moving your body - also like in a car), heat energy (keeping your body at 37C takes energy), protein cells from your food are used to repair organs, and the "exhaust" is everything you excrete, eg CO2, heat, urea and a part of poop and some water

So if you imagine a gram of fat is like a gram of coal - a single solitary chunk. That coal gets burned/used up and the exhaust of that coal is water, CO2, and some noxious stuff. After all the fuel is burnt out of the coal, then you are left with charcoal - another solid by-product of the burning/using up process.

I think it's probably best to think about it in the "fat is reserve fuel" way. It's probably the best analogy

So the "matter" in this case fat, changes form (in the form of CO2, water and urea and other gunk) oh and also some of the matter turns into body cells (did you know that in a year, none of the cells that are make YOU right now will exist?) - so yes mass does still exist in the world somewhere, in the atmosphere as excreted gases and in the sewers as excreted solids.

LOL I always wonder the same thing. Yes, I know it is "burned" but still it has to go somewhere! When I am in the pool or walking.. exercising.. I always imagine all those little calories and fat "blobs" floating around out there somewhere.

I personally send my fat to my skinny friends!

Does anyone have a really efficient woodstove? Mine makes lots and lots of heat with very little smoke or ash. You can't see the heat.

With a body, it's much the same. You give off lots of heat (which you can't see) and a little bit of feces, sweat, hair, nails, urine ...

And you have a husband like mine - who is a very efficient fuel burner - you can get warm just being next to him. He radiates heat - the cats always sleep on him, esp in the winter.

All this poop talk is kind of gross...
But I've always wondered the same thing. I never was very good at science though!

HAHA lockitup!

Hmm, i always got it...i guess you need to have a thing for science...basically understanding how solids can change their chemical form. The fat doesnt really 'go' anywhere, it isnt really excreted, it changes chemical form when the body calls for more energy because its not getting enough energy from the fuel (food) it gets each day. It comes out as body heat (hence the reason physical activity makes you hot; you're using energy i.e. calories. And fat is stored up energy) Thats why a calorie deficit is so important to lose weight.