Q: Help! I haven’t had a period for two months. I recently started an intensive marathon-training programme and haven’t changed my diet; could lack of food be the problem?

Your periods can stop if the energy needed for your exercise regime outweighs your food intake.  This is likely to be the cause as you mentioned that you have started an intensive training programme but you haven’t changed your diet.  Exercise without the correct intake of food can reduce your body fat percentage to a level where menstruation ceases. 

Your body is extremely clever. If you are going through a famine and food is in short supply, your body will shut down your reproductive system. The reproductive system is the only system you don’t need in order to keep you alive. Another reason why this occurs is because your body throws into action a short of natural birth control. It senses that there is not enough food to sustain both you and a baby, so it takes steps to prevent a pregnancy before it can happen.

All you need to do is to increase your calorie intake while you are following this intensive programme.  Your body should respond quite quickly with your periods coming regularly every month.