there are multiple reasons a person might lose their period. so it might not be ed related. loss of periods with ed's is usually more to do with body fat percentage than actual weight. if you've lost a lot of fat, or not taken in enough nutrition, regardless of your weight, that could be the culprit.
you could, of course, if it's possible, also be pregnant. don't ever overlook the obvious! are you willing/able to get checked out by a doctor? that would be the best thing for your health.