Re: Weight loss through calorie restriction less than expected; mathematical modeling

On 9/3/2011 11:30 AM, randy@xxxxxxx wrote:
On Sep 3, 10:14 am, Susan<su...@xxxxxxxxxxxx> wrote:
x-no-archive: yes

Hall K, et al "Quantification of the effect of energy imbalance on
bodyweight" Lancet 2011; 378: 826-37.

"According to Kevin D. Hall, PhD, of the National Institute of Diabetes
and Digestive and Kidney Diseases in Bethesda, Md, whereas patients are
often told that cutting 500 calories a day will let them lose a pound a
week, a more realistic formula is that such a caloric reduction would
lead to a 50-pound loss over three or more years.

Even then, such weight loss is possible only if the calorie reduction is
actually maintained over that time. The standard rules -- endorsed by
the National Institutes of Health and the American Dietetic Association,
among others -- fail to consider that human metabolism responds
dynamically to changes in diet and body composition, Hall and colleagues
asserted.

If a 300-pound dieter could really lose a pound a week by cutting his
regular diet by 500 calories, he would vanish entirely in six years."

Susan

Susan,

This study is not a repudiation of the classic calories in vs calories
out theory but supports it. Heavier fatter peoply have higher resting
metabolic rates and will burn more calories than lighter less fat
folks. It's still calories in vs calories out but with consideration
of how "calories out" changes at different weights/fat levels.
Calories in vs calorie out is still the major driver of weight loss/
gain.

From the paper:
"Furthermore, adults with greater adiposity have a larger expected
weight loss for the same change of energy intake, and to reach their
steady-state weight will take longer than it would for those with less
initial body fat. Using a population-averaged model, we calculated the
energy-balance dynamics corresponding to the development of the US
adult obesity epidemic. A small persistent average daily energy
imbalance gap between intake and expenditure of about 30 kJ per day
underlies the observed average weight gain. However, energy intake
must have risen to keep pace with increased expenditure associated
with increased weight. The average increase of energy intake needed to
sustain the increased weight (the maintenance energy gap) has amounted
to about 0·9 MJ per day and quantifies the public health challenge to
reverse the obesity epidemic."

"population averaging: is WORTHLESS. It is the type of "obvious" math which consistently yields incorrect results. To get a reasonable result from a complex population, you need a matrix analysis, with one factor being AGE, and the other factor(s) being (you hope) the other independent variables, like weight. Of course there may be yet more important variables (eye color?, occupation?, gender? ) sometimes they can be identified, sometimes, you just get BAD results. Studies involving diet, even those not as ineptly done as this, often yield unreproducible results.

An example of the "missing factor" problem were the early studies on the effect of alcohol on stroke and heart disease. Initially it was thought that red wine got results, people STILL quote this. When looking closely at the study population, it was found that people who drink red wine ALSO tended to have a healthier life style than those who drank beer or spirits - adjust for that, and it became clear that ALCOHOL was the factor, not red wine.


.

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