I am a 30 year old male who works out 3 or 4 times a week cardio, weights and has a good diet. As my goal in to acheive a 6 pack before I'm 31 I am trying to drop my body fat by doing more cardio but inevitably I end up losing weight which I don't want to do. Any ideas or advice to help me acheive my goals?
Check out bodybuilding sites for advice, they're the experts on losing bodyfat while retaining muscle size. Beware though many are just there to peddle supplements though that may be the best route.
You could also try using circuit training as your cardio, at least you'll be stimulating more muscle groups especially if there is a lot of impact. Adjust your food intake accordingly (remember eating fat doesn't make you fat, only excess calories make you fat).