Always happy to feed the arrogance of the ignorant. If you're
interested in understanding it, let me spell it out.

1) Your estimate of the calorie budget of a 340-lb person is wildly
wrong.

2) The best estimates are still inaccurate.

3) Supposing they were EXACTLY correct, you would still be missing
part of the equation: energy conversion by thermodynamic systems are
less than 100% efficient. Converting fat molecules to ATP, as one
example, is not 100% efficient. Parts of the fat molecules' energy is
wasted in the conversion process. No thermodynamic system converts
energy without loss. The consequences of this are twofold.

First, the energy content of a pound of fat (as determined by burning
it and measuring with a calorimeter) is not equal to the actual ATP
energy produced from that fat. Therefore your conversion rate of 3,500
cal/lb is incorrect.

Second, the conversion of fat molecules to ATP, and the conversion of
CHO molecules to ATP, are completely different chemical processes. It
would be an astonishing coincidence of two utterly dissimilar energy
conversion processes have EXACTLY the same efficiency. If their
efficiency is not exactly equal, then one process wastes more energy
than the other. The more wasteful process will "burn more calories" to
make the same net energy available to the body.

To make your model accurate, one needs to know the actual efficiencies
of the two processes. If the conversion wastage is accounted for, your
equation must at least account for it thus:

the body's energy need = food/fat energy converted - conversion cost

The conversion cost term will depend on the composition of the food
energy being converted--it will differ between fats, carbs and protein,
and will also differ between simple sugars and complex carbohydrates.

Finally, note that this is a purely thermodynamic argument. This
represents the ROCK BOTTOM analysis; any other terms missing from this
equation can only be subtractive on the right-hand side.

For example, there may be biological reasons that fat mobilization and
fat storage are mutually exclusive, which (if true) would mean that a
person would be incapable of storing fat while in ketosis. If THAT
were so, then a person could eat 5,000 cal/day without gaining weight,
if the body remained in ketosis.

While that exact scenario does not agree with reality, lots of other
factors may be involved. Your ignorance of human biology is likely to
be as profound as your ignorance of thermodynamics, so I wait with
pleasure for your rebuttal that it "doesn't make any sense to you".

Regards,
Len.

It would be funny if it wasn't so tragic.

This one says nothing about good and bad fats.  Insulin resistance is
not
caused by natural fat consumption.  Trans-fats likely play a role in
the
function of insulin receptors, but staturated fat consumption has
nothing
to do with blood glucose levels and the associated insulin response.

Yet another kitchen sink correlation/assumption study.  A suggestion
is made
to eliminate saturated fats at the same time as reducing the GI of
carbohydrates
consumed.  So which is it?  The fat or the starch?

Not a single mention of trygliceride/VLDL effects of carbohydrates
forgetting
about the fact that trans-fats were being fed to the gerbils.  The
original
studies "proving" that saturated fats were bad ignored the role of
carbohydrates
too.  No one questions that you are better off with mono or
poly-unsaturated
fats given the same carbohydrate intake.   The issue in this group is
the role
of carbohydrates themselves in the VLDL and LDL picture.  Eliminating
fat from
your diet will do nothing to solve excessive blood VLDL levels and
increase
the HDL to LDL ratio.  But reducing high GI carbohydrates will lead to
a
dramatic improvement.

Says zero about goodness or badness of natural saturated fats in the
diet.

Another junk study that completely ignores the role of carbohydrates
in the
VLDL and LDL levels in the blood.   Consumption of saturated fats
raises both
LDL and HDL levels.  Consumption of starch increases LDL at the
expense of
HDL (the liver scavanges HDL proteins to construct LDL to transport
all those
tryglycerides formed from excess glucose).

At least they point to the VLDL and LDL increase and HDL decrease in
response
to fat consumption decrease but neglect to highlight that it is the
carbohydrates  that are responsible.   Sure saturated fat increases
LDL but
it increases HDL which they neglect to mention.  And nobody is
defending the
poison called trans fats.

Trans fats are bad for you, is that controversial?