If you're going for a low-carb diet, remember that the way they work is that carbs are the body's 'normal' fuel - when they run out your body starts burning stored fat instead - which is the idea of the diet of course.
The problem is that when you reach this point your body says to itself 'uh, oh; looks like winter's coming along; no food; better slow down' so your metabolism slows. So if you aren't really disciplined you'll become less active, so the weight you lose by burning stored fat you would have burned off anyway in your normal day to day activity.
Plus your brain likes lots of calories to keep sharp, which you normally get burning carbs. Burning fat is much less efficient, so you might start to lose concentration, focus, etc.
So if you're going to go on a low carb diet, make sure you're got the self discipline to keep up your activity level and make sure you get enough sleep and cut down on caffeine etc so you can stay sharp throughout the day.
If you don't have the self discipline, walk to work/get off 2 stops earlier - recommended anyway now the weather's getting better since you see so much more of what's going on around you/use the stairs instead of the lift/have a lot more sex
Oh, and don't eat any cookies .....
