Alright, after trying to lose weight myself with little success, i've consulted a doctor and started a vitamin supplement bar diet, which ensures that I get all the needed vitamins/minerals from my food, and only intake 750 calories/day. All my life i've been a fairly strong person (in comparison with other people my age at least), and i'm worried that if I lose weight, i'll also be losing muscle, and i'd like to still be able to lift the same amount that I used to be able to. So I was wondering, would cardio excercise be such a good idea for me? As i've heard that this can actualy decrease muscle strength. If I want to be able to keep the same amount of muscle that I have at the moment, should I be training using heavier weights with less reps, or lighter weights with more reps? Currently i'm losing about 3lbs/week without any additional excercise, except taking stairs more often and getting off the bus a few stops early. Anyways, if anyone could help me out, it would be appreciated, I don't want to go from being able to bench 140 to only 120 or something.