Due to unresolved endocrine issues, I am obese. My lifestyle is healthy, and phentermine makes me sleepy. How can I lose weight?

Obesity and endo. It will be difficult to lose weight until you resolve underlying endocrine issues.
Diet/Exercise. The formula is actually very simple. Even if a patient says they're eating "next to nothing", if s/he I not losing weight, then that amount is too much for them, given their level of exercise. This is true for everyone, so don't feel singled out. The other option is considering bariatric surgery (lap band and other similar procedures).