Roch,
Glad to see your making a commitment to working out. I can understand needing the motivation right now and not wanting to see any weight gains by muscle mass. Here's the quick bottom line. The right combination of weight and reps for a resistance training session can help you gain strength and not add any mass. The important thing to realize is this: Cardio will raise your metabolism for 4-6 hours at most after your workout. Resistance training can raise your metabolism for 24-48 hours after a workout depending on the intensity.

The end game is to cut carbs, burn fat, and raise your metabolism. This will maximize your loss. I recommend a simple resistance program 3 days per week. Your welcome to take a look at my routine for an example. Better yet a Personal Trainer can help set up a program suited to your goals and help you get going.

Regards,
Lux