I was not arguing for studying theory over practical experience- but to argue that he is far from an expert at either approach.
It's true that most effective fitness techniques lack any solid theoretical basis and were discovered by self experimentation. However, his knowledge level of these practical fitness techniques is shallow.
For example his workouts were copied nearly verbatim from the book "Body by Science" but are missing important advice from that book on how to perform them safely and effectively. He also seems unaware of the methods developed by self-experimentation/bodybuilding pioneer Vince Gironda, which are generally more effective than the methods he talks about in 4HB.
Another example- The low rep/low duration/infrequent lifting methods in 4HB don't work without EXTREMELY high effort/intensity levels. He does mention this in his book (I think he says lift like you have a gun to your head), but the vast majority of people can't do this without specific mental techniques that increase intensity. By leaving "intensity mental hacks" out of his book, the workouts will do nothing for most people.
I'm glad that he's popularizing alternative fitness and nutrition ideas, but at the same time I'm frustrated that he didn't take the time to do a better job of researching and understanding what's out there first.
Do not read this if you don't know anything about this Tim Ferriss person
I suspect anyone here is less different from Tim Ferriss than they'd like to be able to justifiably claim (see here, here, here, here).
I don't mean Tim the Result. Results are clouded by what has been brought to attention in one of the 2009/2010 rationality quotes here
I mean Tim the method.
The varieties of achievements he's done are behaviourally distinct from living normal life. They are not so complicated to learn though.
I invite you to ask the following question: What is one thing he's done I haven't that probably I could do, and what is the explanation I invented to myself for not having done it? Do I truly believe this explanation? Think for a minute before reading more
When I ask this to friends who read some of his stuff, I see three kinds of answers:
This is impossible for anyone who doesn't have property X (where X is always a fixed characteristic, like place of birth, blondness, impeccable genetic motivation)
We have very different values, and there is no point in trying that about which I don't care - interestingly, with every new book, there are more interests on the table to be considered "not my values", but no one suddenly came to me and said: Wow, finally he cares about throwing knives! I have reason to try after all. Are my friends values narrowing in proportion to Tim's expansions?
There are a lot of people who don't want to have more money, learn languages, work less, or travel a lot, but there are much fewer people who besides all of those don't want to exercise effectively, learn quickly, improve their sex lives, throw knives, memorize card decks, program, dance tango, become an angel investor, be famous, write books, cook well, get thinner, read quicker, contact interesting people, outsource boring stuff and so on...
The third kind is personal attack. People claim he has property E, which makes him Evil, and his evil either is proof of the falsity of his accomplishments, or is proof that emulating Tim means you are a dark creature who shall not pass through the gates of heaven. The most interesting E's are "He's a brilliant marketing man, selling profitable lies, but marketing is Evil." "He doesn't understand survivor bias, and how lucky he was, and has not read outliers to know it takes min4000 hours to get good at stuff" "He's a good looking ivy league blonde, this makes him evil" (this girl probably had in mind Nietzsche's lamb morality, from Genealogy of Morals).
What is one thing he's done you haven't that probably you could do, and what is the explanation you invented to yourself for not having done it? Do you truly believe this explanation? Would your best rationalist friend truly believe that explanation?