My diet consists of lots of protein, and barely any carbs.  I drink 2-3 gallons of water every day, I eat a ton of tuna, salmon, etc, and my only carb intake is from Creatine.  I am also on Whey.  I work out 1-2 times per day, and I do lose energy.  I may start having some carbs before my work out, but so far I've been doing fine.  I dropped from 210lbs to 160lbs in about 4 months.  Then I gained muscle up to 175, and then lost some more fat again, and now I'm back down to 160, and stronger than I ever was.  Working out makes you stronger.  Your diet multiplies your potential.  If you know what I mean.