The data this guy uses is pretty old. Even though hes says that they have stood the test of time.................. this puts into question a lot of theory.

That being being said there several interesting point in this presentation. When he talks about BMR at around 4 minute mark the drop noted at around 30 day mark is 25% (which is huge). What I found interesting is that BMR went up in lean people in first 1-2 days.

What I want call in question here is the assumption that people would fast for days on end. This seems like an extremely marginal action. In fact I have never ever met anybody who subscribes to the idea of total fasting. Even Muslims, when they fast for a month, would break the fast in the evenings and then restart in the morning with a light meal.

Around the six minute mark he also mentions that the gradual decline in BMR over extended periods is not protected by the presence of extra body fat. This is actually quite reasonable, as fat reduction can only occur by a sustained routine of controlled diet intake and exercise (maybe a little fasting thrown in as well).

He also makes some really good points on protein metabolism.