Todd Moody wrote:

>  Everything I've seen indicates that protein is more thermogenic
> than carbohydrate or fat.

I try to see the body regulatives in a way that they make sense.
Sense for survival or just for optimal functioning of all resources like
mental ability, muscle ability, endurance, coping with several
challenges like toxins, heat, low water supply etc..

In this picture it wouldn't make sense to consider just macronutrients.
Any original macronutrient supply, from meats, vegetables, seeds, roots
etc tend to be high in protein (in terms of RDA) and a little short on
energy. Particularly short on carbohydrate energy if you exclude tubers.

What *would* make sense?
One thing that comes to my mind at first is, that the body needs to have
a "feeling" of abundance of energy before it would invest into the
rather costly (in terms of energy) thermogenesis.

As soon as some shortage signals were there, the best and most effective
way to spare would be to downregulate the body temperature a little.
-- what actually happens via the thyroid if calorie reduction is
encountered.
If the "abundance" signal comes again, then body temperature should rise
up to the *optimal* temperature level (37 deg C in all parts).
Above this level the satiety signals should come up, shutting down the
dietary intake. Unless some other demand was there.
Like maybe shortages of some kind of micronutrient.

Of course health conscious people like you would not think  of any
micronutrient as beening short on supply.
It could be that we either underestimate our needs under certain
conditions (like high carbohydrate intake or high protein intake) or
overestimate the micronutrient activity of our sources (pills, farmed
food items).

>> He says if a human had access to abundant sources of low protein/
>> high fat food -- he would store the fat, raise his leptin levels and then
>> stop eating.
>>
> I think this is true, but the problem seems to be the setpoint at which
> the leptin kicks in.  If, for example, the leptin turned off appetite
> when body fat exceeds 12%, this would be great.  But we know that this
> is not always the case.

Why should the body trigger it's appetite at a certain body fat
percentage (like 12%). Obviously it doesn't.
As we don't see really fat animals (except those preparing for
hibernating or in extreme temperature conditions) some other mechanism
should be working as the natural "stop".
Long before, or at least in time.

> But "wasteful" is what we want, isn't it?  It means that we have to do
> more metabolic work to digest the food, which in effect raises the
> metabolic rate.  If we take two meals of equal calories, one 50% protein
> and 50% fat, the other 12% protein and 88% fat, we will need to use more
> energy to proces the first meal.  That, it seems to me, means that less
> of that meal is available to be stored as fat.

Of you took two meals of equal calories, then the overhead of fuel
derivation from protein (you mentioned 10%) should already be calculated
in, shouldn't it?
Then the calory derivation from protein would be exactely the same, just
slower.

Anyway the 10% overhead for 50% protein would only be 5% of the whole.
A sum which is hard to distinguish from one bite more or less.

> Anecdotally, I find that I gain weight if my lowcarb diet is also
> low-protein.  After a while, I seem to develop an insatiable appetite,
> and I tend to eat large quantities of these low-protein, high-fat foods.

I recall you had such a success on the anchell diet with small little
part of white rice etc..
This should have relaxed the carbohydrate shortage signals.
On the other hand low-carb means high-fat.
Fat is what's fuelling thermogenesis from brown adipose, so there
shouldn't be a reason to spare on fat-thermogenesis (I suppose there are
other ways of thermogenesis than from brown adipose - thin persons can
have fever).

Cheers,

Amadeus
(I'm happily not yet falling out of the 70-72 kg frame,
but imagine that the time might come)