Andrew: 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.)

Good question. In being brief I have misrepresented the facts slightly.
There was only one patient who put on weight. This was due to water
retention during her menstrual cycle. But others maintained their weight on
1,000 kcal, high-carb diets for short periods. Why they didn't lose is
unclear from the data.

Andrew:
> > 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%!

Voigtlin states: "The coefficient of digestion is the percentage of ingested
food that is digested, absorbed, and utilized by the animal. It is a measure
of nutritive efficiency and, in the carnivore EATING ITS NATURAL DIET of
meat and fat, the coefficient approaches 100%." (emphasis mine).

Much of what we eat today is *not* natural to us as a species. A proportion
of this will pass undigested through the gut. Even herbivores waste around
50% of their intake through imperfect digestion and absorption. As we are
not herbivores, it would not be unreasonable to assume that our gut is at
least as inefficient at processing such material, particularly if it is
eaten in the raw state.

Andrew:

> 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.

Much of the gut mucosa is replaced every three days. Are those cells
reabsorbed? I reiterate that 1g per kg lean body weight is the accepted
figure for dietary protein intake if from animal sources; 1.5g if from plant
sources. If you know otherwise, please give me a reference. Although, having
asked that, these figures will probably have been revised downward recently
as 'healthy eating' insists that we eat less meat and more flour, so I
wouldn't put too much trust in them.

Barry Groves
http://www.second-opinions.co.uk