I would have to say from my experience using them, and all that I've read about them, that intermittent fasting diets are marvelous.

In regards to the post above, when I IF I don't skip meals a vast majority of the time and I am never hungry/unsatisfied. Check out the introductory/about articles at leangains.com for some very great info on intermittent fasting protocols. I very much like his recommended 8 hour feeding protocol. Haven't heard complaints about it.

Also, from an evolutionary standpoint food would have been in constantly varying quantities, and if an 'energy conservation' state existed as described it would have been active almost all the time, but primitive hunter gatherers were almost always relatively lean and disease free. Supposedly at low levels of body fat (6-10%/can see your abs) your body still has MONTHS worth of ketones to use as energy in the form of your stored body fat.

Side thought: I've heard reference to studies that some amount of cellular repair gets activated only in times of fasting.