Yep, I was going to bring up the old bygone, abandoned-before-it-even-had-a-chance Phentermine "phase" too.
If I'm right (tho MedKiwis and ScienceKiwis please correct me if I'm wrong) Phentermine is one of the strongest and one of the most clinically successful appetite suppressant/weight loss drugs a Doctor can prescribe. It's usually not even written out for patients who aren't at least obese or morbidly obese and NEED to lose weight for health reasons. I think its sometimes seen used for BED patients too now?
Hamber wasn't even slowed down on that stuff. She gorged herself on half a pizza
while musing about how she wasn't even hungry 
She spun some completely nonsense, incomprehensible gibberish later about how "not feeling hungry" scares her. It scares her, you guys. She purposefully stuffed herself while basically being on medical-grade Speed. A puff on a cigarette or vape ain't gonna do it. She is beyond hope.
Fellow Lolcow Chantal/Foodie Bloopy has had a similar experience of porking herself up while on Vyvanse. These women are utterly astonishing.
It's not THAT great, but it's pretty good stuff. There are lots of pay-for-play clinics that will prescribe it even if you're just 20lb over (welcome the TMI ratings, but I got hooked on it back in the phen fen days when I was a normal size, I just WANTED to be 2 instead of a 10, so for $150 a week, I got my packet of pills). Phenfen was the shit, too bad fenfluramine was taken off the market.
That said, it is pretty strong stuff and could easily help her shed 100 or two. It's not the strongest stuff on the market anymore only because there are new drug combos that combine things a chemical cousin of phentermine and topamax (anti-depressant, migraine med, and anti-binge eating/drinking med), or phentermine and wellbutrin. There's also one that's an injection that combines phentermine (or something in the phentermine family) and a diabetes drug.
When amber took the phentermine, she made a huge production of having to take her blood pressure all day, and blah, blah, blah. Like, yeah, it's an upper. Those aren't great for your heart, but you know what's worse for your heart? Carting around a quarter ton of fat. I'd assume if she were willing to take it, a reasonable doctor would give her phentermine (which comes in different doses, maybe 2-3 low doses a day are what she needs instead of high doses?), lasix and some other bp med.
Amber makes a production over everything. It would be SO easy for her to take phentermine and follow WW or the diet the bariatric doctor gave her, or something like nutrisystem where you nuke all your meals, and lose weight. But her identity is so tied up in her obesity that the very thought of getting on track freaks her the fuck out. I'm sure she's also a little afraid of not being able to binge, but if medication makes you not want to eat (phentermine is anorexia in a bottle), wouldn't she feel some control over her life?
I can't get into her mindset and understand on any level why she's clinging to the fat like a security blanket, rather than taking the various pills that will change her life, but it seems like the weight is as much of a security blanket as the binges.