On birth control-started period early?

I have been on birthcontrol for a year and half now. I always start my period on the same day each month in accordance with the bc package. This month I started a day early which has never happened. The only thing that I can think of being different is I have been on the South Beach Diet for two weeks. Any ideas on why this happened?On birth control-started period early?
Definitely a new diet or new exercise could throw the body off track. I was on BC for over 10 years and occasionally would miss a period all together(even when I wasn't having sex at all). So anything can contribute. If you ever go a week early or late then I'd be concerned and talk to your doctor about it. But a day isn't a big deal.
leading cause is STRESS... dietary intact may play a role but in my experience it has been stress... relax don't worry...it should go to normal next month.... This happen to me.. just continue to make sure that you take at the same time each day as well.... hope this helps...
This is normal it's all because of the hormone changes in ur bady caused by the birth control!