I personally think that it depends on your attitude. If you're someone who normally eats what is considered "junk" food or a lot of fast food loaded with preservatives, then yes, you're likely to gain weight. I know quite a few women who are on the pill and have diets high in fruits, veggies, and poultry that is mainly home-cooked, and they drink plenty of water and their bodies don't change. My body hasn't changed as a result of nuvaring, and I too eat a lot of fruit, I abstain from cow and pork meat and I drink plenty of water and I try to incorporate at least a little bit of exercise (like not focusing on parking too close to a building entrance, taking the stairs instead of the elevator, walking certain distances instead of driving, etc). I also try to get at least a good hour of exercise walking in every week.
So basically, you can take a bc and be conscious of your diet. I have one friend who was already chubby, she eats a lot of chips, fast food, cakes, etc, drinking minimal water, and she blew up like a balloon.
But yeah, talk to your gyn about lower dose pills, apparently yasmin is a very low dose pill. Nuvaring is also great because of the minimal hormones (it has less than half of the hormones that the pill has).