Re: Fastup/Slowdown

[Guest guest]

This is my interpretation of the diet rate papers:

" Body Fat Content Influences the Body Composition Response to

Nutrition and Exercise " GILBERT B. FORBES

says that " the total weight change is influenced by the initial body

fat content "

" Rapid weight loss and lean tissue: evidence for comparable body

composition and metabolic rate in differing rates of weight loss. "

on A, Kreitzman S, Brodie D, A.

specifically addresses weight loss by " the overweight person " and

concludes that very low calorie diets are not " associated with any

detriment to body composition " .

The on article is concerned only with overweight persons achieving

normal proportions and is a subset of the cases considered by Forbes.

Forbes paper considers both thin and obese persons: " Overfeeding: In

experiments of at least 3-weeks' duration, the weight gain of thin

people comprises 60-70% lean tissues, whereas in the obese it is

30-40%. Underfeeding: In humans, there is an inverse curvilinear

relationship between initial body fat content and the proportion of

weight loss consisting of lean tissue. "

In addition, the section that Rodney highlighted (***Another

factor is the magnitude of the energy deficit: as energy intake is

reduced, lean tissue makes up an increasing fraction of the total

weight loss.***), seems to indicate that increasing the severity of

caloric restriction will also increase the rate of loss of lean

tissue. Bodybuilders try avoid loss of lean tissue during their

slim-down (trimming) phase by consuming most of their calories as

protein and essential fatty acids.

I think the Forbes paper is more applicable for people with BMI in the

normal range. In any case, the Fast-up/Slow-down type of diet may have

some advantages. As long as you keep up your daily exercise, your

Chinese ad libitum buffet weekend can build up your muscles and

eliminate dietary deficiencies (assuming no junk food), and your

calorie restricted weekdays will keep your weight in check by slowly

reducing any weekend gains. Serious CR practitioners should check to

make sure that the weekly calories average out to the desired level

of CR.

Tony

[Guest guest]

Hi Tony:

Let me try to clarify the point I was making about the section of the

Forbes abstract that I triple-asterisked, by giving a numerical

example:

Where the abstract says: " Another factor is the magnitude of the

energy deficit: as energy intake is reduced, lean tissue makes up an

increasing fraction of the total weight loss " I understand it to mean

the following:

Suppose someone has a current metabolic rate of 2000 kcal/day and

wishes to lose weight. He can vary the 'magnitude of his energy

deficit' by either consuming 1900 kcal or, alternatively, 1500 kcal.

In the first case the 'magnitude of the energy deficit' is 100 kcal,

in the second case it is 500 kcal.. I take the section I triple-

asterisked to mean that with the 500 kcal deficit the proportion of

LBM lost will be much greater than in the case of a 100 kcal

deficit.

In other words, only a relatively small proportion of the weight lost

will be LBM if the rate of weight loss is slow. But a comparatively

high proportion of the weight lost will be LBM if the rate of weight

loss is rapid. As I understand it this is a separate phenomenon

from, and in addition to, variations in the proportions of LBM being

lost depending on the amount of fat available to be trimmed down.

And Berardi's article (the link you provided) does specifically state

that this applies in the cases of both weight loss and weight gain.

That is, rapid weight loss ***or gain*** is associated with a higher

proportion of the weight change being in the form of LBM, than in the

case of slow weight loss, or gain.

So if the Forbes double-asterisked quote is really true, and if

Berardi is correct when he says that the effect is symmetrical both

up and down in the magnitude of caloric deficit, then the inescapable

conclusion must be that YO-YOing weight rapidly upwards and slowly

downwards will have the effect of increasing LBM, no matter the level

of fat tissue.

Now I do not know whether Berardi and Forbes are correct. (And

Berardi seems to rely on Forbes for his information). But if they

are correct then this is highly significant. I am trying to locate

the full text of the Forbes article to find out what his evidence

is. More on this later, perhaps.

Rodney.

>

> This is my interpretation of the diet rate papers:

>

> " Body Fat Content Influences the Body Composition Response to

> Nutrition and Exercise " GILBERT B. FORBES

> says that " the total weight change is influenced by the initial body

> fat content "

>

> " Rapid weight loss and lean tissue: evidence for comparable body

> composition and metabolic rate in differing rates of weight loss. "

> on A, Kreitzman S, Brodie D, A.

> specifically addresses weight loss by " the overweight person " and

> concludes that very low calorie diets are not " associated with any

> detriment to body composition " .

>

> The on article is concerned only with overweight persons

achieving

> normal proportions and is a subset of the cases considered by

Forbes.

> Forbes paper considers both thin and obese persons: " Overfeeding:

In

> experiments of at least 3-weeks' duration, the weight gain of thin

> people comprises 60-70% lean tissues, whereas in the obese it is

> 30-40%. Underfeeding: In humans, there is an inverse curvilinear

> relationship between initial body fat content and the proportion of

> weight loss consisting of lean tissue. "

>

> In addition, the section that Rodney highlighted (***Another

> factor is the magnitude of the energy deficit: as energy intake is

> reduced, lean tissue makes up an increasing fraction of the total

> weight loss.***), seems to indicate that increasing the severity of

> caloric restriction will also increase the rate of loss of lean

> tissue. Bodybuilders try avoid loss of lean tissue during their

> slim-down (trimming) phase by consuming most of their calories as

> protein and essential fatty acids.

>

> I think the Forbes paper is more applicable for people with BMI in

the

> normal range. In any case, the Fast-up/Slow-down type of diet may

have

> some advantages. As long as you keep up your daily exercise, your

> Chinese ad libitum buffet weekend can build up your muscles and

> eliminate dietary deficiencies (assuming no junk food), and your

> calorie restricted weekdays will keep your weight in check by slowly

> reducing any weekend gains. Serious CR practitioners should check

to

> make sure that the weekly calories average out to the desired level

> of CR.

>

> Tony