Craig Smith wrote:

>But a two-week test I did a year ago indicated that my break-even
>point is about 4000 calories, and I suspect it may not be even
>that high, since I don't seem to lose much unless I stay around
>2500 calories.
>
>I know rules of thumb aren't inviolable laws or anything, but I'm
>thinking that this particular guideline needs to be adjusted
>downward for very obese people---the fatter you are, the more
>suppressed your metabolism seems to be.  Which is perplexing---
>has anyone read any studies about *why* this should be so?
>
>

Here's a guess.  The more obese a person is, the more of his or her body
weight is fat, and fat is less metabolically active than muscle (and
skeletal weight remains constant).  The 14-15 cal/lb. "rule" is linear,
and the actual "break-even" function is almost certainly non-linear.
 And obesity contributes to other metabolic imbalances (e.g., insulin
resistance) that skew the relationship even further.  Incidentally, I
think women have to use a lower rule -- something like 12-13 cal/lb. to
break even -- because of different body composition.  Obviously,
activity patterns also throw the rule off.

I mentioned the Pennington and Kekwick and Pawan diets of about 2600
cal/day, which is coincidentally about what Stefansson and Andersen
consumed on average during the Bellevue experiment in 1928.  Using the
15 cal/lb. rule, a diet of 2600 cal. is a "break even" diet for an
individual weighing about 173 lbs.  For me, currently at 235 lbs. (I'm
quitting the DIT experiment, after gaining 2 lbs. over the weekend),
2600 calories would be about 11 cal/lb., which would be considered quite
hypocaloric.

Todd Moody
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