I was exactly where you are several months ago. I was *always* tired. I woke up tired if I'd worked out the day before!

In addition to protein, are you getting enough fat? I recently switched to a high-protein, moderate- to high-fat diet and have never had as much energy (or stamina) while trying to lose weight.

Just in case you're "afraid" of fat (I was, it's still hard to drop the idea that it's a killer), there is A LOT of research now coming out that the fat-heart-disease link was overblown, at best, and completely falsified, at worst. Good Calories, Bad Calories (Gary Taubes) and In Defense of Food (Michael Pollan) are good books, Fat Head is a pretty funny movie and there are dozens of articles on it online.

Work out at night? If you are really tired throughout the day. Before when I got fat and lost weight all my work out's were in the evening time after work then i'd stay up a few hours after then go to bed. I also worked out on an empty stomach because i'd always go for a run after my work out video and I could never run with anything in my stomach. I lost the weight I wanted and reached my goal. Unfortunately over the years I've lost motivation and everything and anything and here I am again a tubby. But try night time work outs and yes they work just as good.