first of all- low carb isin't an Ideal weight loss plan if you ask me. If you go that rought, make it a temporary thing. Carbs are the the fuels that not only give you energy, but they also help speed your metabolism. If you eat a carb (preferably complex, whole-grain) in the morning, it will give you the energy you need to burn more calories more efficiantly. Even if it is the ONLY carb you eat, a breakfast carb first thing in the AM is always good (and it burns off as water and CO2- protien burns of as a toxin). Try eating carbs before 2pm and none in the evening- it works well. AND DON'T SKIP MEALS!!! It slows your metabolism big time. 5 small meals are better that 3 medium, or even small ones!
Then of corse there is the topic of low fat... yeah, good idea, cut it where you can, but more important than that is low SUGAR. Sugar gives you automatic energy, so your body doesn't use it's reserves! Bad, bad, bad! You want to burn off those 30 lbs, make your body work for it! You can do without that sugar low too. Stay below 5g per serving when you read lables!
And lastly, exercise- duh...you knew that though. Get your heart rate up for 30 to 45 minuts 3 to 6 times a week! You can do this all with diet, but do you want to? If you are already doing aerobic exercise, and are at a plateau, swich it up. Use weights- try 3 sets of 15 to 20 reps per exercise. This will keep your mass down, but will tone you from the inside out.
You probably have heard most of this before, but if I stress nothing else, I stress that SUGAR IS BAD and eat a grain in the am- best advice I can give you! Hope it helps!