Irregular Periods.......Eating Too Little or Exercising Too Much could be the reason says Dr Deepa Agarwal, Best Dietician in Hyderabad.
This can slow your metabolism down. The body will slow itself down in response to a lack of food or excessive amounts of exercise to conserve itself. Studies show that if you do aerobic exercise for more than 1 hour a day, your metabolic rate can drop by as much as 15%.
In addition, eating too little can have the same effect. If you are eating too little, so much so that your fat stores cannot cover your calorie deficit, your body will begin to use lean mass to get the energy that it needs. This study shows that over a 6 month period of a 25% calorie deficit, your metabolic rate will only drop about 6%.
Studies show that as long as you%u2019re eating at enough of a deficit that your fat stores can cover, your metabolic rate doesn%u2019t change too much. If you do go over that deficit, though, your metabolic rate will severely drop in order to protect vital organs (this is a real %u201Cstarvation mode%u201D response from your body).
Against all logic, adding some extra calories from fat and protein to your daily macros may help. Try it for a few days, and see the results. If you exercise a lot, try cutting it back some and give yourself some extra rest days. My personal advice is 4 days maximum of hard training during the week.