[possiblywrong]

> "For these reasons, I'm actually a bit surprised that the author's data matches the theory so closely... The fit is so perfect I actually suspect he... ah... played with his data slightly after the fact. A "fortuitous" choice for alpha is obviously helpful too."

Author of the linked blog post here. I made the comment that "if I had instead chosen 12, or 13 (for alpha), the resulting predictions would not agree nearly as well." This is perhaps overstating the "luck" of my initial midpoint choice. Here is a quick plot showing the same data with predictions using 12, 12.5, and 13: http://imgur.com/lP5sjwB

(Note also that a better least-squares estimate of alpha is actually about 12.7.) Even these "endpoints" still look to be in reasonable agreement with measurements. That is, if 12 to 13 calories per pound really represents most of the range of variability among the (male) population, then one can likely make useful predictions without needing to be spot-on with their choice of alpha.

Of course, it's a valid question whether 12 to 13 really covers a large chunk of the distribution. Are there men out there with alpha<10, or >15, for example?