On Sat, 23 Aug 2003, Barry Groves wrote:

> Andrew Millard wrote:
> >
> > It seems incredible
> > to me that adults on a 1000-calorie diet could gain weight, as their
> > metabolic expenditure ought to exceed this with even a modest amount of
> > activity, and if the energy is not coming from burning of body reserves,
> > then our fundamental understanding of where biological systems get their
> > energy from is in doubt.
> >
> > Did these studies control for the activity levels and energy expenditure
> > of the patients?
>
> I hope you will bear with me as the following is rather long.

It is long, but it does not answer my questions.  That calories are
measured in a bomb calorimeter is only tangentially relevant: the
calorimeter is very efficient at extracting energy from the food and thus
the measurement provides an upper bound on what the human body can extract
from its food. So, how does someone on a 1000 calorie diet, but who must
be extracting less than this from the diet, gain weight even if they lie
in bed all day?  (Human adults' basal metabolic rate is 70-80 Watts
depending on sex and age, so the minimum kilocalories required per day is
about 3600*24*75/4200=1542.)

> In fact the digestive process is quite inefficient so that all we eat is
> not even absorbed by the body, let alone used by it.

True, though this is not what you say on your website
http://www.second-opinions.co.uk/carn_herb_comparison.html
where human and wolf digestive efficiencies are given as an amazing 100%!

I also take issue with the following:

> Body cells are in a constant state of death and rebirth. No matter how many
> birthdays you have had, very little of you is more than eight years old. The
> primary function of dietary proteins is used in this process: for the
> manufacture and repair of skin, blood and other body cells; to make hair and
> finger- and toe-nails. The amount of protein needed for this purpose is
> generally accepted to be about one gram per kilogram of lean body weight. As
> meats contain approximately 23 grams of protein per 100 grams, a person
> weighing, say, 70 kg (11 stones) needs to eat about 300 g (11 oz) of meat,
> or its equivalent, every day just to supply his basic protein needs. Even
> eating lean chicken this would contain some 465 calories. These calories are
> not used to supply energy, they contribute nothing to the body's calorie
> needs and so must be deducted if you are counting calories.

But only the skin hair and nails are excreted as protein (plus excretion
in breastmilk).  The other body cells' protein is broken down and recycled
within the body or excreted as urea, so the protein intake required for a
protein mass-balance is not as much as you say, or you have listed too
many tissues as protein outputs.

Andrew

 =========================================================================
 Dr. Andrew Millard                              [log in to unmask]
 Department of Archaeology, University of Durham,   Tel: +44 191 334 1147
 South Road, Durham. DH1 3LE. United Kingdom.       Fax: +44 191 334 1101
                     http://www.dur.ac.uk/a.r.millard/
 =========================================================================