A friend asked if I was familiar with this diet, and I found myself giving an impression that may be worth sharing.
I know that this claim is bullshit:"proven to promote longevity, overall health, and reducing excess fat."
Briefly, the only way you could essentially prove anything medically is to conduct a large scale randomized trial. Barring that, whatever evidence one has is weak to say the least.
Large RCT's (several hundred to thousands of subjects) are basically impossible because reliably enforcing what people eat is not feasible (you'd basically have to confine people, and then doing so would introduce confounders that would obscure your results, like what type of person could handle being controlled to this degree?)
So, claims like this are never based on large RCT's (if nothing else, they're incredible expensive to run). Instead, they're based on surrogate markers, like serum glucose, CRP, IGF-1, also parallels in rats, etc. These things are based on hypotheticals, theories of metabolism, and other science-y stuff that seems like good evidence, that's based in actual real research somewhere (rather than Deepak Chopra's crystals or Muscle Man's "proven formula"), but is several steps removed from actual testing in real people. Basically, you can construct a biochemical rationale for how almost any diet works. You can even get some research findings to back it up, like effects on CRP in mice. But the chances of this actually having the stated effect on metabolism and weight etc gets diluted to nothing better than calorie reduction. And even that has its issues.
A great example is the weakness of the energy balance theory of weight gain. On the surface, this seems obvious. Weight gain is caused by consuming more calories than you burn or poop. But that's like saying the reason a tumor grew in your lung is because it consumed more calories than it burned up (some gyn tumors can be 40 pounds). So yes, it's an energy balance issue, but you don't grow tumors because you eat too much. There's a huge debate about whether the energy balance theory is right, or whether weight is an endocrine problem.
Lastly, that's not to say this is a bad idea. The only way forward here for the individual is individual testing. So, if this diet appeals to you, and you're getting decent results, awesome. Just be sure to use your personal results--weight changes, sense of wellbeing, etc--rather than anything the diet itself claims as evidence of progress. If it's working, keep it up. If you find effective tweaks, great. But if it's flagging, particularly if it's flagging because you find you're just not that into avocados anymore, you're probably finding a fatal flaw.
I'm guessing you're familiar with the Tim Ferris approach, which I like. The trouble is, Ferris is a unique individual, so what works for him is unlikely to work for others.