What are the possible health risks associated with weight loss of 65lb+ over a 2 year period. bmi dropped from 30 to 19.8 in a 20 y/o female through restrictive and selective eating. ?

If you lost your weight intentionally with diet +/- exercise, you have nothing to worry if you are feeling fine in all aspects (physical and mental) and you are currently eating well with a balanced diet. You can stop further weight loss at this point, keep your BMI between 20 - 22. For a lady at your age, your menstrual cycle correlates well with overall health. Good luck.