Can you determine natural bodybuilding potential? Is it possible to determine if a lifter is a natural or steroid user? The answer is yes to both questions.

The formula. The following equation is derived scientifically, studying approximately 300 winning drug-free strength training athletes and bodybuilders from 1947-2007. For more information please visit Casey Butt’s article, Your Maximum Muscular Bodyweight and Measurements.

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H = Height in inches

W = Wrist circumference located at the hand side of the bony lump on the wrist (known as the styloid process)

A = Ankle circumference at the smallest measurement

BF% = The bodyfat percentage at which the ankle and wrist circumferences were taken

The information. Again, for more information on this subject, please visit Casey Butt’s Weightrainer.net.

Potential Variance. The natural bodyweight potentials listed below are derived using a wrist circumference of 7.5 inches, and an ankle circumference of 9.5 inches. These numbers are reasonable for the heaviest of natural lifters. (Note: the author’s wrist circumference is 8.0 inches, and ankle circumference is 10.0 inches at a bodyweight of 280 pounds. So you can see that for a natural lifter under 220 pounds, 7.5 and 9.5 are very reasonable numbers)

For a 0.5 differential in BOTH numbers (a lifter’s wrist is 8.0 inches and ankle is 10.0 inches instead of 7.5 and 9.5), the weight variance using the formula would be an additional 5.2 pounds of lean mass. In simple terms, for every additional inch of circumference (from either ankle, wrist, or both combined) above the potentials listed below, a lifter could have an additional 5.2 pounds of lean mass.

Again, keep in mind that the numbers used to derive natural potential (7.5 wrist circumference and 9.5 ankle circumference) are at the high end of normal for a natural bodybuilder with under 20% bodyfat. Therefore, a reasonable maximum potential variance for natural lifters from the below numbers would be plus 3 pounds. For smaller wrist/ankle boned lifters, the numbers could be smaller by up to 10 pounds.

The numbers. Using the above formula, and inserting 7.5 wrist inches and 9.5 ankle inches, we derive the following natural bodyweight lean body mass potentials for a 6% bodyfat percentage. Again, the derived numbers below are lean bodyweight, which means total bodyweight less fat. It is not total competition bodyweight including the 6% bodyfat.

The reduced formula with wrist and ankle circumferences and a 6% bodyfat percentage is…

H^1.5 (0.31037632)

Height, 66 inches = 166.4 lean body mass potential. Competition weight = 177.0 pounds

Height, 67 inches = 170.2 lean body mass potential. Competition weight = 181.1 pounds

Height, 68 inches = 174.0 lean body mass potential. Competition weight = 185.1 pounds

Height, 69 inches = 177.9 lean body mass potential. Competition weight = 189.3 pounds

Height, 70 inches = 181.8 lean body mass potential. Competition weight = 193.4 pounds

Height, 71 inches = 185.7 lean body mass potential. Competition weight = 197.6 pounds

Height, 72 inches = 189.6 lean body mass potential. Competition weight = 201.7 pounds

Height, 73 inches = 193.6 lean body mass potential. Competition weight = 206.0 pounds

Height, 74 inches = 197.6 lean body mass potential. Competition weight = 210.2 pounds

Height, 75 inches = 201.6 lean body mass potential. Competition weight = 214.5 pounds

Height, 76 inches = 205.6 lean body mass potential. Competition weight = 218.7 pounds

A personal analysis. Last year I religiously measured my bodyfat percentage as I lost weight and packed on muscle. My estimated lean body mass was 178 pounds, at a height of 5′10″. This tells me that I was approximately 4 pound shy of my natural limit. Judging from my muscularity at the time, I believe this number to be dead on.

Bottom line. It is possible for a natural lifter to exceed these numbers by a very small percentage. But, it is virtually impossible for a natural lifter to exceed their potential by more then 10 pounds. Based on ankle and wrist circumference, I think it is safe to say that a lifter who exceeds their natural potential by more than 5-10 pounds lean mass is suspect.

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5 Responses to “Determining Natural Bodybuilding Potential”

1. No Nonsense Muscle Building says:

   January 16, 2009 at 10:28 pm

   Hey this article was very interesting. I have often wondered if there was a way to tell potential. Do they use this in testing for natural vs. non natural bodybuilders?

   They person that came up with that sure has a brain to come up with that formula.
2. Steve says:

   January 17, 2009 at 12:35 am

   No, they don’t use it as an indicator for natural competitions. But as a bystander, if someone is 10 pounds over their potential, you can pretty much know for sure that they have used something at some point.

   Nice looking website, btw.
3. Casey Butt says:

   March 7, 2009 at 2:02 pm

   Hi Steve,

   I think that while these equations very well could be used to spot steroid users, they shouldn’t be the final word. After all, however UNLIKELY it is that someone naturally surpasses the predictions it would be very limiting and demoralizing to suspect every legitimate natural who does approach the predictions. In fact, that would probably guarantee that no competitor ever even tries to surpass them for fear of persecution …which would create a self-fulfilling prophecy.

   I think the equations should be applied to competitors and, based on the results, further blood tests, etc, could be applied afterward — though this would not detect drug users who haven’t yet reached even their natural potentials.

   I do, however, think equations of these forms should replace the BMI. Especially in medical fields where classifications of overweight, diet recommendations, drug dosages, etc are based on height and weight, but usually completely ignore the impact of bone structure. It’s a very simple adjustment to fit the lean body mass equation to the general untrained population for the sake of such things.
4. Muscle and Brawn says:

   March 23, 2009 at 8:26 pm

   Casey, I have changed some of the wording a bit in this article to leave it a tad bit more open ended. Thanks for your insight and inspiration.
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9. jimmy says:

   December 7, 2009 at 7:00 am

   hey…..This is one of the best blog for Nature body building.You given maths wise description its good for easy learn.thanks …..