After reading the excellent writeup that Jay got from another list he's on
(which he forwarded to this list last week -- "Why high-energy diets work
better for weight loss"), it still seems to me that it is indeed possible
to take in more calories than you expend and not gain weight on low carb.
Comments appreciated on what follows.

Say, for the sake of simplicity, that you needed 100 calories a day to
supply your energy needs.  Take in 100 calories of carbs only, then, and
you'll not gain or lose weight.  Take in 120 calories of carbs and you
gain, 80 calories and you lose weight.  So far so good.

But, as pointed out last week, things become more complicated with fat and
protein.  Jay's writeup states that "...carbohydrates have but one
purpose: to supply calories that your body can use for energy."  The
assumption with mainstream calorie counting is that the same goes for fat
and protein.  Take in 100 calories of fat and/or protein and current
dietary wisdom tells us that you break even just like the 100 calories of
carbs.  Not so.  Because of inefficiencies in converting fat and protein
to glucose -- as well as the body's need for fat and protein to maintain
and rebuild the body -- you'll need much more, calorie-wise, when low
carbing just to break even.

According to the writeup, about half of the fat calories consumed are
actually available for energy use.  So, in our example, you'd need 200 fat
calories to break even.  And with protein, the first 20% is used to simply
meet the body's needs for protein as protein.  The remaining 80 calories,
even if they could be as efficiently converted to glucose as
carbohydrates, would still be a deficit.  And we know now that protein
cannot be converted to glucose nearly as efficiently as carbohydrates. I'm
not sure what the calorie equivalent would be if one

Anybody disagree with the above?  I've simplified by assuming that only
carbs, or protein, or fat are consumed.  What happens with the mixing of
the three in the real world?  If, for instance, only fat and carbs were
consumed.  Would the carbs be preferentially used for energy and the fat
stored?  What about fat and protein only?  Protein and carbs?

I'd appreciate further enlightenment!

Jim