re: free day... on the dvd's he says to keep it to maybe one or two cheat meals but i've heard that people have better losses if they basically eat what they want, no portion sizes that I'm aware of
Okay my non BT related opinion would be, if your close to goal then a proper free day particularly consisting of starches rather then sugar and fruit would be important as your leptin stores are likely to be low. If you have a lot to lose, not so important as your more likely to have ample leptin and if there is a problem with leptin it is more likely your body is ignoring it rather then being deficient. However, particularly if your eating little, it might be useful in slowing down your bodies adaption as well as being useful in replenishing glycogen stores for those that exercise a lot.
But back on the topic of leptin, if memory serves me correct, when they first discovered leptin they actually injected obese people with leptin thinking this would be the miracle cure for fat loss and guess what? It did nothing... why? because they already had plenty of leptin but their body was ignoring it.