On 12 Feb 2004 19:16:05 -0800, (kvs) posted:

"J Stutzmann" wrote in message ink.net...
Thermodynamics --- a law we can't live without! [grin]

It's not a law but a collection of laws. Thermodynamics is about the
aggregate statistical behaviour of systems, assuming a Boltzman
distribution for the energy in the states of the system. You cannot
reconstruct the microphysics of a system starting with thermodynamics.



wrote in message
news:slbWb.19977$032.64937@attbi_s53...
In sci.med.nutrition tcomeau wrote:
: Maybe the lesson to be learned is that calories really have little
: bearing when it comes to weight gain or loss in humans.

1) Please learn to trim quotes
2) Have you somehow forgotten the laws of thermodynamics? It is quite
simple: if energy in energy out, the body will gain mass.

Wow. The reverse of a nuclear explosion! There are no mass-energy
conversions in chemical reactions.

Who said there were?

You gain mass because the various
chemical reactions in your body that keep you alive start storing some
of the mass that you consume instead of extracting chemical energy
from it and excreting the mass.

Or you store excess chemical energy in your food intake as chemical
energy in the body. A gram of fat stores 9 calories, and a gram of
carb and protein stores 4 calories of energy.

Now what triggers this mass storage?

Excess energy in the system.

It isn't thermodynamics,

Thermodynamics is just a succinct statement that energy can neither be
created nor destroyed, something that some here seem to overlook, at
times.


it is the design of the the cellular
chemistry and cell microphysics.

No, excess energy in the system is just stored as chemical energy in
the body tissues. No excess, no storage.

Different people have sufficiently
different microphysics (e.g. number of insulin receptors in their cell
membranes) that assuming that one energy balance model works for
everyone is absurd.

Less receptors just means the reaction is slower. The end point is
the same however.


One person who consumes several slices of bread
or any other starchy food will respond to the induced insulin spike by
producing more heat while another will respond by storing fat created
from the starch (which is a collection of glucose molecules). The
system of each of these individuals will obey the laws of
thermodynamics but clearly the result is different.

But of course this different heat output is insignificant. Otherwise
folks would overheat. How is extra heat generated when muscular
activity is not increased? The BM generally produces enough metabolic
heat to keep folks comfortable. (In reasonable climates, that is

If
energy out energy in, the body will lose mass.

Yes, just like in the fission of Unranium nuclei....

WTF are you talking about? 1000 calories of food in, and 500 calories
of energy out, and you will have 500 calories of excess energy stored.

That will be a couple of ounces of fat, thankyou very much.

Moosh