Wednesday, February 20, 2008

How to keep arm size while dieting

I received a great question over the weekend about dieting and losing muscle.

To paraphrase the question, it was quite simply, "If I am not losing muscle mass while I am dieting, then how come my upper arm has lost a quarter inch in girth?"

Well, to get to the bottom of this problem we need to look at some very basic math.

Lets take a 16 inch arm as an example...

( I apologize for the bashed up knuckles and hairy armpits)

If you took my arm and cut it in half right through the middle of the biceps, this is what it would look like...

(A hypothetical cross-section of my arm, labels included)

You will notice that my arm circumference can be described as circular. If we remember all the way back to grade 11 math class, we might remember that we can calculate the circumference of a circle from its radius and vice versa (I say 'might', because I had to look it up on google)...

(The radius is the distance from the center of your arm all the way to the skin on the outside)

Since we know that the circumference of a circle can be calculated by the equation Circumference = 2(pi)radius, we can determine how much (or little) of a change is needed to the radius of the arm to create a quarter inch loss in girth...

So for a 16 inch arm like the one in the picture above, the radius would be 2.546 inches. For that same arm to lose 1/4 of an inch in its circumference, the radius would have to be reduced to 2.507 inches, a loss of a little less than 1 mm.

So if I lost a little less than 1 mm of subcutaneous fat from my arm (which is more than possible, and barely detectable with most skin fold calipers) I could lose a whole 1/4 inch of my arm measurement without actually losing any muscle mass.

Fat loss happens everywhere,


PS- If you are interested in an easy way to lose fat without losing any muscle, check out EAT STOP EAT here and learn more about flexible fasting for weight loss.

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Redlefty said...

How many emails did you have to go through before you could find one that gave you an excuse to post your flexed bi pic? :)

Anonymous said...


As I've been fasting I've noticed that I'm gradually looking "smaller," though more defined.

I'll take it.

Brad Pilon said...

Hi Redlefty,

I actually sent the question myself! (Just Kidding)

But I did originally have a picture of Lee Preist's arm up and it just looked ridiculous!


Brad Pilon said...

Hi Richard,

I'd be interested in hearing about your progress so far.

Great post about the fat bomb breakfast drink....sounds tasty!


john said...

Good post, it is easy to mistake fat loss and water loss as muscle loss.

There are multiple area's where we store water as well. Within muscle cells, in extra cellular space(around cells), within fat cells...

Regular consumption of food and more specifically carbs and sodium tend to cause us to hold water compared to a complete lack of food. This constant changing water content of the body is usually what causes quick changes in measurements. Its very hard to actually 'lose' muscle if you're working out.


Patrick said...

you just love shooting your own bod and posting it don't you. Any excuse to do so is good enough for you my friend.

Beyond that, just wanted to give you some heads up, some props and another op to post your pic.

I am into my third week with Monday's as my stop day. I am on STOP from dinner Sunday evening to Monday Dinner (5pm to 5pm). This time was recommended when in deep debate and conversation with one of our colleagues JB. It is going well, I have more easily than assumed beat the fasting challenges I thought would hit hard.

Next I am going to add in my standard program with some of my old school bodybuilding diet tricks.

I started at 232lbs and __ bf% (we'll keep that a secret for now) and feel great, haven't started training or any supplement regime yet (that starts next week) and plan to change dramatically starting next Monday with an empowered EatStopEat nutrition plan, supplementation and body weight training program for 12 weeks. Should look good just in time for some new pregnancy pics with my wife, 2 daughters and our bump that is a boy.

you revived a part of my nutritin knowldege that I had relegated to teh abyss of my brian and empowered me to be better and challenge conformity in my everyday business and personal life. MORE PROPS: I fel great on Mondays, am more productive and with all the greens product I have in the am, green tea and coffee I am flying high, love it. So good I am debating another STOP day along with another trick I will report back on.

Do you have any pre EatStopEat pics of you or members/clients. I am thinking fat to fast to fabulous. I was also wondering if you could post some images of pre STOP and post STOP (24hrs) not tweaked for before/after images. Such as no tan, shaving etc...I think alot of people get that it works for the fat, but let's show them how impressive it can be for the already lean. I also think many people need to know you live like that and keep lean all day long 365d.

Thanks Brad, keep up the great posts and information. ESE is pretty impressive and I look forward to posting my personal results.

Mike Groom said...

Nice post Brad and nice bicep shot! I love the separation in your bicep, something I will achieve this year.

Tim Peters said...

Brad, believe it or not ;-), the conclusion you reached has nothing to do with the initial size of your arm. Some people will find this obvious, but most will find it paradoxical, so here goes:

Say the initial circumference and diameter of your arm are C1 and D1, respectively, and their final values C2 and D2. Then losing a quarter inch in circumference means:

C1 - C2 = 0.25 in

But because circumference is pi times diameter, that's exactly the same as saying:

pi*D1 - pi*D2 = 0.25 in

Divide both sides by pi, to get:

D1 - D2 = 0.25 in / pi ~= 0.0796 in ~= 2.02 mm

and it makes no difference at all what the value of C1 (or D1) is: whether your arm is 16 inches, skinny as an electric toothbrush, or big around as the Earth, if diameter shrinks by about 2mm (same as the radius shrinking by about 2mm/2 = 1mm), the circumference shrinks a quarter inch!

And note that subcutaneous fat (stuff you can pinch through the skin with calipers) isn't the only thing at work. In addition, we have intramuscular fat (picture a nicely marbled steak), which also shrinks. And when someone switches from calorie balance (or surplus) to an overall calorie deficit, but keeps exercising, the body taps muscle glycogen stores for energy. Get 4 kcal of energy from that, and you lose a gram of glycogen along with 3-4 grams of associated water, and all that stuff occupied space too.

Most people don't have a lot of intramuscular fat or muscle glycogen in the upper arm, but same deal applies: any shrinkage in radius is magnified by a factor of 2*pi ~= 6.3 when circumference is measured.

So if big numbers on a tape measure is the primary goal, stuff yourself with carbs to store as much glycogen, and grow as much of all kinds of fat, as possible ;-)

Brad Pilon said...

Hi Tim,

Thanks for the comment.

I think I must have rambled a bit in my post, as my point really didn't have anything to do with the initial size of the arm.

My point was simply that very small changes in the radius can cause big changes in the circumference.