Late period probably from change in diet and exercise...?

My period is about five days late, and I'm having hot flashes. I imagine it is from changing to a high fiber diet and increased exercise since this can affect the menstrual cycle. Pregnancy is pretty unlikely I think although my fiance and I are ually active. I'm 24 so menopause is even more unlikely. My main question is if it is from the dieting, is this unhealthy? Should I cut back and try to ease into the diet more?