LBM Change at Varying Levels of BF%

[Guest guest]

Hi folks:

I have now read the Forbes article on which the data in the Berardi

article (which Tony linked) was based. It is quite interesting.

Perhaps the single most interesting stat is that it seems the

principal determinant of LBM for any individual is body fat weight.

I never would have believed it, but the data suggest that compared

with a lean person an obese person may have as much as 80% more LBM,

because that amount of muscle, bone, etc. is necessary to function -

support, move, supply blood to - an obese body. This is derived from

Figure 1 on page 360. It shows data for females and it suggests a

female with BF of 55% would have 82% more lean body mass than one

with 16% BF. Amazing. And it really does strongly support JW's long

stated assertion that lean mass is lost when weight is lost simply

because the body no longer needs as much LBM to function at the lower

weight.

This same Figure 1 does also support Tony's assertion of a

progressive increase in the proportion of LBM lost as BF% declines.

This appears to be especially true at very low levels of BF%.

But in addition, the data support the Berardi point that **rate** of

weight change is also a major factor determining proportion of LBM

change with weight change. There are, however some difficulties

interpretating the data here.

The first difficulty is in the data range. Of the 28 observations in

the chart demonstrating this phenomenon 79% of them are in subjects

whose body fat exceeds 44 pounds. Indeed the majority of the

observations are in subjects with over 65 pounds of fat weight -

HUGE. At these higher weights it does seem clear that **slow**

weight loss is dramatically better at preserving LBM than rapid

weight loss. Therefore, at these weights at least, the

fastup/slowdown principle does seem to be supported. But if you

weigh this much in the first place and manage to get your weight

down, why would you WANT to rise five pounds rapidly?!!!! But these

data hardly support the principle at BF% levels of people as they

move their weights down to approach CRON-type levels.

There are no observations at all in Figure 2 of those on extremely

restrictive diets below 65 pounds of fat weight. Even for those in

the middle category of restriction there are no observations for

subjects starting out with less than 30 pounds of body fat. The

category of least restriction in this study was for everyone

consuming over 1000 kcal/day - while this does have observations all

the way down to quite low fat levels, most of us here would regard a

range of 1000 kcal/day and up much too broad to provide the kind of

information we would want to see.

However, one can try to extrapolate back to see what the data might

look like for people with the amounts of body fat people here are

most likely to have. (Extrapolation may yield quite unreliable

conclusions). With the foregoing qualification, using extrapolation

it seems that at 15% BF slow weight reduction might lose 55% as LBM

while rapid weight gain might add 65% LBM. But at BF of 10% any

effect, indeed if any, is likely to be very modest. That is the LBM

change would probably not vary with rate of weight change.

So my conclusion from the data in the Forbes article is that it is

unlikely much if any benefit can be gained from fastup/slowdown at

CRON-type weights (i.e. BF%s between 6% and 10%). If we had a lot

more data for people with lower fat burdens (i.e. with fat weights of

10 - 25 pounds) then we could be more confident about the magnitude

of any benefit. But for now, the table in Berardi's article showing

big variations in gain or loss of lean body mass depending on whether

weight change is fast or slow, while certainly apparently applicable

to obese people, probably does not apply to us - at much lower body

fat levels.

Rodney.