My period has always been on time every month (give or take a few days) for the last 4 years until 3 months ago. I had started to take some diet pills (Trimspa) and that month, my period was over 3 weeks late. And when my cycle did show up, it was very short and very light. It was not my regular menstrual cycle that I usually have. During that time, I did take a pregnancy test and it had came out negative and I also had stopped taking the pills because I was worried I might have been pregnant. Since that very short cycle, my period still hasnt shown up from that time and I dont know if I should be worried. I never started up taking the pills again but my period is still no where in sight. So does diet pills affect your cycle?? Thanks for any help.