woman ?

I'm not 100% sure the answer to that question. I do know that your diet affects the chemistry greatly in your body. Excessive weight loss or weight gain will change your schedule. Stress will change your schedule. This past week I started a new type of lifstyle change in my diet and I am also running behind, although i feel it coming. I know I'm not pregnant. So from my own personal experience, I believe it can. Also increase in exercise might delay it a little too. That's my 2 cents worth.

ANYTHING can change the timing of your periods. From travel, to stress, to change in diet to exersize, everything has an effect on your body chemestry. Different factors in the environment can have it's effect as well, that's why women who live or work together often sync-up; the girls in my dorm at college all started and ended within about a week and a half of one another. If you're late and worried then I'd say get a pregnancy test, the ease of mind is deffinately worth the cost. But any change is probably just your body adjusting to the new situation you've put it in.

when I first started running it was late and way lighter than normal. Then the next month it would be normal, then back to light again. 2 years later, I'm back to being pretty normal, but I'm also on 3 month birth control pills so that makes a difference too.