I recently lost 20 pounds. i have not had a period since i lost the last 5 pounds. my bmi is 19.8. did i miss a period because of weight loss?

Irregular cycle: Many things can cause changes in the regularity of your cycle besides pregnancy. It is not uncommon for cycles to be irregular for the first couple of years after starting. Additionally, illness, stress, excessive exercise, excessive weight loss and diet changes can cause changes in your pattern. If your cycle does not return soon, see your doctor for 'secondary amenorrhea'.

Possible: It is possible that the weight loss could have effected your cycle. Especially if you have been exercising allot or not eating meals. However your BMI is normal. It would probably be prudent to check a home pregnancy test if you are sexually active. If it is negative see how you do for a month or two and I would anticipate you should cycle. However, if persistent problem get checked.

Possibly: Losing weight can affect the menstrual cycle and cause irregular periods. However, if you are sexually active, a pregnancy test is in order to rule out pregnancy as the cause of late period.