From: caf@omen.UUCP (Chuck Forsberg)
Subject: Re: Adiposity 101
Organization: Omen Technology INC, Portland Rain Forest
Date: Wed, 23 Dec 1992 07:12:42 GMT

In article <dnsurber.725054011@node_26400> dnsurber@lescsse.jsc.nasa.gov (Douglas N. Surber) writes:
>In <1992Dec21.002143.26900@crd.ge.com> stpeters@crd.ge.com (Dick St.Peters) writes:
>
>>In article 133@ky3b.UUCP, km@ky3b.pgh.pa.us (Ken Mitchum) writes:
>>> In article <dnsurber.724007610@node_26400>, dnsurber@lescsse.jsc.nasa.gov (Douglas N. Surber) writes:
>>> |> Your point seems to be that one pound of fat is the equivalent of some
>>> |> fixed number of calories, thus if one eats so many extra calories, he
>>> |> will gain so many extra pounds.
>>> 
>>> Yup. 3500, if I remember correctly.
>
>>Actually, there's a conversion efficiency.  N calories of food intake does
>>not become N calories of fat.  The efficiency is very high for conversion
>>of food fat to stored fat, but for food protein or food carbohydrates to
>>stored fat a significant percentage of the nominal calories is used up in
>>the conversion process.  I can't remember reliable numbers, and my sources
>>are back home, but numbers like 90% for fat and 60% for carbohydrates and
>>proteins come to mind.
>
>>I'm pretty sure a pound of human fat has very close to 3600 calories.
>
>OK.  I guess that this is the crux of my question.  Just how consistent are
>these conversion efficiency numbers between people?  Also, how precisely can
>these numbers be determined for a single person?
>
>It would seem that it is likely that two people could have a conversion
>efficiency difference of several percent, maybe even 10% or more.  If this
>is the case, then two people could eat the same amount, excercise the same
>amount, and still one gain weight and the other not.  And this is only one
>metabolic path.  What about the efficiency of the gut in extracting various
>components, protein, carbohydrates, fats, from the ingested food?  What about
>the efficiency of converting sugars into ATP?  My uneducated guess is that
>these could combine to produce substantial differences in food to fat/exercise
>efficiency.
>
>Of course I could also be totally wrong.

The relative efficiencies of the macronutrients is covered in
Adiposity 101.

If you accept Gordon's definition of overeating (sufficient
energy input to allow maintenance of fat mass above population
norms), overeating could mean anything between 800 and several
thousand calories (kcal/d) depending on the individual.

And it really doesn't make any difference if the conversion
factor is 1000 or 5000, except for the velocity of weight
change.  The individual will undereat or overeat, and eventually
starve to death or explode.

Of course this doesn't happen except in a few extraordinary
instances.  There is a feedback system that regulates body
weight within fairly narrow limits.  Gordon doesn't believe in
it, but it is described by the Set Point Theory.

-- 
Chuck Forsberg WA7KGX          ...!tektronix!reed!omen!caf 
Author of YMODEM, ZMODEM, Professional-YAM, ZCOMM, and DSZ
  Omen Technology Inc    "The High Reliability Software"
17505-V NW Sauvie IS RD   Portland OR 97231   503-621-3406
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