I gained 16 pounds, lost 20 of that after the Luprolides had worn off. Lost most all of my body hair soon after starting. After 2 & 1/2 years on, it took a bit more than 2 & 1/2 years to recover as much as I have. Lupron killed one of my testicles so my loss of libido is pretty much permanent. Doc said I was lucky to have kept one testicle alive and functional.
I appeared to have aged maybe 15 years or so while I was on the stuff, gained fat lost muscle despite being an over-the-top athlete. Better now. Got very emotional and fatigued, still take afternoon naps.
Some research on what your pituitary gland actually does will fill you in on the details, as Luprolide chemicals shut it down completely and there are many profound ramifications to that. Stuff like your kidneys leave more water in your blood (water weight gain), the quantity and thickness of mucous in all of your body nucousal membranes - lungs included - changes drastically and your thyroid slows down your metabolism so you burn less calories in your base metabolic rate. There are changes in immune function as well - I got the Shingles despite having had the vaccination against that.
If Luprolide chemo works though, the cost is small compared to the alternative.