I'm starting to go on the pill nov. 30. When will this pill start to "work"

also, i am worried about gaining weight. I run/walk 6 miles a day and i eat very healthy.. should i be concerned

The First packet of birth control pills may not provide you with the same level of protection against pregnancy as the following months' pill packets will because during the first few weeks you take it... there lies the chance of an egg being released before you take the first pill. It's a good idea to use a back up method until you have completed your first pack of pills.

Some women don't gain weight on the pill and some do, it really depends on your body's reaction to the hormone. I have been on the pill for 2 years and have not gained a pound. Every woman is different. Since you walk and get plenty of exercise...I wouldn't worry to much. Good luck with starting your pills.