It should be noted that Ferriss wrote a 2008 article describing how to effectively put on 30 pounds overnight by dehydrating oneself before a weigh-in and then rehydrating before competition begins. [1] The fact that the miracle muscle gains mentioned in Tim's new book are also roughly 30 pounds should not go unmentioned.
Tim specifically addresses the 34 lbs of muscle gain in 28 days in the Mixergy interview. It's not the same routine of dehydration/rehydration for competition.
I think I see here 34 pounds of muscle in 28 days. How did you do that?
Timothy: So that was just so people know the circumstances. I was supervised by a Ph.D. at San Jose State University, and we used hydrostatic weighing, which is underwater weighing, for body composition. The way I did it was with two 30-minute workouts per week, which means it was literally four hours for the month. So in this case it is the 4-hour body. And there were a number of protocols that I followed.
The first was the exercise protocol, which was and we’ll talk about this I’m sure more, following the minimum effective dose. So how many seconds of tension with a specific weight or load do I need to trigger muscular growth in certain body parts? And you can figure this out. So I was using a very slow safe protocol to achieve that eliminating momentum to the extent possible, tracked everything like a scientific experiment.
And then the second protocol was the eating protocol. So you have to eat a lot to gain 34 pounds of muscle. I also lost three pounds of fat and lowered my cholesterol from 222 to 147. And that involved eating, but improving insulin sensitivity so that was preferentially put into muscle tissue as opposed to fat tissue. Then also taking supplementation to improve protein synthesis and things like that.
So at the end of the day it was a combination of very small things used together.
I'm sure he has more exhaustive logs that support his claims but the quote above (the same story was in Wired a few weeks back) isn't detailed enough to prove that Tim gained 8.5 pounds of muscle per week.
I was unfamiliar with hydrostatic weighing so I looked it up. Hydrostatic weighing appears to measure water displacement to figure out the body's density and hence fat to muscle composition. The density of muscle is 1.06 g/ml and fat is 0.92 g/ml. [1]
A gain of 30 pounds of water (1.0 g/ml) would show up as roughly equal gains in fat and muscle since water's density is about at the midpoint between fat and muscle. Ferriss's claim is +34 pounds of muscle and -3 pounds of fat.
I'm certain Ferriss gained lots of muscle in his four-week trial. His methodology isn't all that different from Gallon Of Milk A Day (GOMAD) plus the Starting Strength workout plan, both of which I've personally used to some success. That said, the freely available quotes don't give all of the necessary information. If you happen to buy the book, please share with us.
[1] fourhourworkweek.com/blog/2008/01/18/how-to-cut-weight/