Weight loss rate as a function of body fat

TR0berts

MelanieCN77 wrote: »

I literally don't understand the question, I think it's your use of the word "function."

He's using it in the mathematical sense, as in y is a function of x in the equation y=x+3. For every x, there is only one y.

Tacklewasher

Posted in the "Daily Fat Energy Limit" thread, (and was having deja-vu) so here it is again. http://community.myfitnesspal.com/en/discussion/10600746/daily-fat-energy-limit

Here is the link to the abstract on the research paper.

https://www.ncbi.nlm.nih.gov/pubmed/15615615

Works out to ~31 Cal per lb of body fat per day.

I'm about 65 lbs of body fat, so my max per day is 2,015, or a bit over 1/2 lb per day. Now that's not going to happen as I'm not prepared to eat that little, but there is a limit to how much fat can be burned in a day.


Now that thread goes on to discuss how the science is not settled on this, that it may be less than the 31 cals etc.

heybales

So lets call an avg man 2500 TDEE, hitting avg 92% fat as energy source for the day. Or 104 total & 95.8 fat cal/hr.

Except for 3 squares a day, where insulin is elevated for 4 hrs each time and energy source is carbs he ate that aren't needed to be stored, and fat eaten - 12 hrs gone.

12 hrs x 104 cal/hr = 1248 daily calories from stored source,
12 x 95.8 = 1150 from fat source.

1150 / 31 = 37 lbs of fat needed to support that research paper - which is theoretical in nature.

If man is 20% fat @ 180 lbs - then right on for maintaining weight.

Theory paper - take an existing study (MN starvation study) and attempt to read some things in to it neither measured specifically nor purpose of research. Not the same as the Aragon and Schoenfeld meta-analysis studies.

But I know they have research where they had people in metabolic chambers for 24 hrs and confirmed that avg 92% fat as energy source for the rather sedentary lifestyle in that mini-room.
I'd have to find the research to confirm - I know some were athletic too, because after baseline day they are doing workouts for that research.
And I could easily see them being under those pounds of fat. So in that theory fat should not be able to support their TDEE.

I think the major thing wrong with that paper is the aspect of LBM is what was dealt with, but muscle mass is usually what is thrown out when it's used as a basis for something.

And we all know those starting a diet lose some initial LBM as water weight, and glucose stores in muscles are usually maintained at artificially lower levels than potential. (I know, management of that water takes energy so it does have a caloric value behind it)
And as you have less mass, you need less blood volume and water stores - so less LBM needed there too.
Even though muscle mass could be exactly the same.

I'd be curious how they think the number is even less than 31 cal/lb fat daily.