I was assuming that you already had your thyroid/endocrine system checked out? When I had hypothyroid I turned into a blob with no energy. Also, it really helped me to see a naturopath and nutritionist as I wasn't getting answers from GP's and was written off with "it's anxiety or depression." I found out I have all kinds of food intolerances and that can do a real number on your body. But, you didn't mention any GI problems. Do you sleep at night? Sleep disorders also can effect your energy & weight gain. Just ideas. Good luck!