I'm with Roy on everything he said.
Whilst losing weight, it is almost impossible to maintain muscle mass. Even if you continue to hit the weights regularly (4-5 times a week), you are still at a calorie deficient state, so your energy has to come from somewhere, and unfortunately it doesn't all come from your fat stores
Simply, to lose weight, it's as easy as having a lower caloric intake than you're expending. That is, you need to eat less calories than you're burning. It's simple science. No matter what you eat, if you are caloric deficient, you will lose weight. What you eat whilst doing this dictates WHAT you lose though (fat, muscle, water, etc), so it's not good just to eat 2000 calories worth of beer a day
For a steady and healthy weight loss progress, aim to eat about 500 calories less than what you're burning. If you do lots of cardio (a 10km run burns a LOT of calories), you can eat more to compensate. Any less than a 500 calorie deficit and you'll notice too large a drop in energy and more likely to feel hungry and binge eat (drink beer)
Also, I don't think you'll enter a state of ketosis with an intake of 30g of carbs a day. I would think a figure of 5-10g would be more accurate.
Good luck Pete!