Can Exercise Affect Your Period? Dear BeingGirl Experts, My period is overdue by a week, and it still hasn't come yet! I know I'm not pregnant. I am 18 years old and my body fat is around 16%. I work out three times a week for an hour in the gym, but am otherwise not much involved with exercise. Is missing a period like this normal? Thanks, Lilly --- Dear Lilly, Exercise can affect your period, but you would be an endurance athlete exercising vigorously and most days for that to likely be the cause. There are times you will miss a period. If you are sure you aren't pregnant, other causes of skipped periods can be stress, eating issues or illness. Your pattern of exercise does not sound intense enough to cause amenorrhea (lack of a period), but your low body fat may be an issue. If you miss a second period, contact your gynecologist/healthcare professional to discuss what you are experiencing. Hope this is helpful, Your BeingGirl Experts Wondering if you can exercise affect your period? Get answers from the experts at BeingGirl.com.