[PortfolioManager]

I am a science man, so I become excited with scientific studies about fat loss and such.

The below article discusses the maximum calorie deficit you can get into without eating your Lean Body Mass (LBM). When you are cutting, retaining muscle is the key and as you are aware, muscle burns fat. So the article below will help you generate your calorie intake for fat loss.

http://anabolicminds.com/forum/weigh...m-dietary.html

Determining the Maximum Dietary Deficit for Fat Loss

Originally Posted by bits from the article

Key source: Alpert SS. A limit on the energy transfer rate from the human fat store in hypophagia. J Theor Biol. 2005 Mar 7;233(1):1-13.

Now, empirically and based on research, it’s well established that…

a. fatter individuals lose more fat and less lean body mass (LBM) than leaner individuals; and
b. bigger individuals lose weight more quickly

So imagine my surprise when this little theoretical paper (note the journal title) showed up on my Pubcrawler last year (1). Titled, “A limit on the energy transfer rate from the human fat store in hypophagia”, it examined (from a somewhat simplified and theoretical way) exactly the question I gave above: what is the maximum rate at which the body can derive energy from fat stores to cover a diet induced deficit while sparing lean body mass.

It’s a nasty little paper, filled primarily with equations, explanations of those equations and some more equations to boot. Headache inducing to be sure. I’ll spare you the details. Based on a somewhat simplified analysis of what data exists (including the seminal Minnesota semi-starvation experiment), they conclude that the maximal rate at which fat stores can provide energy to the body is 290 +- 25 kj/kg which is approximately 31 kcal/lb of fat per day.

So, if you are carrying a mere 10 lbs. of fat, you can sustain a 310 cal/day deficit.
20 lbs. = 620 calories.
30 lbs. = 930 calories

You get the idea and this is not difficult math. Multiply your total fat mass in pounds by 31, that’s how much of a caloric deficit that fat mass can support on a daily basis.

Say we have a 180 lb male at 15% bodyfat. He has 27 lbs. of fat, and his maintenance calorie intake is 15 cal/lb or 2700 calories. With 27 lbs. of fat, he should be able to sustain a caloric deficit, from diet alone, of 27 lbs. fat * 31 cal/lb = 837 calories/day. So he could reduce his calories to 1863 (ha! 10 cal/lb) and shouldn’t lose any LBM at that level of intake. He should get a weekly fat loss of just over 1.5 lbs./week.

If the same 180 lb guy was at 10% bodyfat, only 18 lbs. of fat, he could only sustain a 558 calorie/day deficit (2150 cal/day or 12 cal/lb), he’s down to 1 pound per week. By the time he’s at 8%, he’s down to 14.5 lbs. of fat and a total deficit of 446 calories/day and about 2/3 a pound of fat loss/week. Oh yeah, if he were a fat **** at 30% bodyfat, that’s 54 lbs. of fat, he could sustain a deficit of over 1500 cal/day and lose over 3 pounds per week of pure lard; of course he’d only be eating 1300 cal/day. Again, the above all seem to roughly pass the reality check in terms of what we see in human dieters.

Now, one implication of the above is that, as a diet proceeds and your fat stores shrink, your net deficit has to decrease. Ok, step back, take a breath and read that again. More importantly, note my use of the word ‘net’ in the first sentence of that paragraph.

[PortfolioManager]

My calculation:

My BMR (the number of calories you'd burn if you stayed in bed all day):

15 calories x 209 pounds = 3135 calories

How many calories to sustain the max deficit (I have 30 pounds of fat based on around 14% bodyfat:

31 calories x 30 pounds of fat = 920 calories

targeted calorie intake for maximum fat loss without losing any muscle mass:

3135 - 920 = 2,215 calories

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I will probably add around 200 to 300 calories here and there depending on my workouts.