LOL. I think we can just put that hypothesis into the category of … “no shit sherlock”. 
Alpert’s calculations determined the slope of the line at various points on the process in the starvation process, so I’m not sure that we can say he was only testing the fumes in an empty fuel tank … he also captured the initial change in FFM as fat contribution first began to be constrained and found that that constraint was a linear function of the total fat mass. He was able to extrapolate that in both directions and to speculate a figure for the theoretical maximum rate. And I think you are correct that is is just a speculation … but he was able to compare all the subjects in Keys study to back test his hypothesis.
But yeah we still come down to relying upon “the weasel Keys”, damn his eyes. I wish that all George Cahills data from his starvation study were available because he had catheterized subjects and was measuring all their circulating energy substrates. At the very least I’d like to know if they fit on Alpert’s curve.
I’ll tell you a secret. I don’t expect to ever have a “healthy” BMI. I am currently at the top of overweight flirting with Obese. I’ll tell you why I don’t expect every to be healthy … for my height my healthy range is 59kg to 79kg. I don’t expect to grow taller from this point in my life, so below 79kg is what I have to hit if I ever want to be healthy weight.
But according to DEXA scans my current lean mass is 80.380 kgs. Even if I could lose all body fat, I would still be 1.38 kgs overweight. It shows you how crazy the idea of using BMI to set your goals is, well at least it’s crazy for a dense bastard like me.
Oh nice application, yes that would be intellectually quite stimulating. I can well imagine how the flight dispatch scheduling software since might be a different pace.
I have a similar story. In 2000 I made partner on Wall St in a company that spun off from the risk division of JP Morgan, but I was at the coal face as a software architect developing risk modeling for credit derivatives. Also quite an intellectual challenge. I’ve not worked in such a challenging area since … but when I left in 2002 I told everyone I could that CDOs would blow up the economy and 6 years later … they did exactly that. But I didn’t have a podcast back then and no-one was listening. Now when I warn people that type 2 diabetes will explode our health care if we don’t change course … well I have a few listeners 