Why would anyone ever lift any weight at all if they aim to lose muscle mass? Weight lifting helps in maintaining or developing muscle, period.
Anyway, it may not be optimal at all for your health, but if you want to maximize muscle loss, avoid exercise altogether. If you do exercise and it burns your muscles as energy, it means you are past the point where there is practically no fat to burn anymore... Which means, zero curves or breasts. And unless your genetics naturally make you super skinny, as in, fat is hard to find at all, as soon as exercise burns muscle, I'm pretty sure you're past a danger line where you put a burden on your global health.
You see, exercise needs muscles. The body won't burn muscles for exercise energy unless it's in serious lack of nutrients. It would be its last resort, just before making you faint.
I'm not an expert, but I did listen in physical education and biology classes, and as far as I can tell, moving without fuel or fat is dangerous, period.
On the other hand, though, cardio exercise will probably help in fat redistribution. Even when the total fat percentage doesn't move much, or even when it increases, it's proven that visceral fat tends to diminish with cardiac exercise. (If you want to learn more, to the conditions that you live in Canada and understand French (._.), you can watch the Découverte episode on "Le grand défi Pierre Lavoie" on
www.tou.tv) Visceral fat is fatty tissue that surround the organs in your abdomen. Less fat in those areas, if the fat mass doesn't change overall, means more fat outside of those areas. This equals better health, but also better curves.