Well, honestly, many women who are somewhat overweight, find that if they eat healthily during the pregnancy, they don't necessarily put on much weight, if any at all.
You need to eat well so that you nourish your body, but you wouldn't need to take in extra calories like a woman normally would, as your body already has a good storage right there.
My mother was overweight all of her life, and never gained in any of her three pregnancies, and we were all healthy, large babies at birth.
Being at a heathy weight is especially best to enable you to get pregnant to begin with, but I think if I were in your shoes, if I felt the time was right otherwise, I wouldn't worry about necessarily losing the weight first. I would just get back to my healthier lifestyle while ttc. Chances are it would take a few months anyway, and you could already be back to taking better care of yourself by then.