Here you have a young woman who is 654 pounds when the episode starts. She visits Dr. Nowzaradan, in Houston, seeking gastric bypass surgery. She does well initially. Just by changing her diet Bettie Jo gets down to 599 pounds and is cleared for surgery.
But this is where things begin to go wrong. For one thing her husband is not on board. He openly admits he LIKES being needed by Bettie Jo, because at her highest weight she needed help just to move from room to room in her own house. He is afraid of her dumping him if she succeeds. The night after her surgery, Bettie Jo's husband does not even stay at the hospital. Then after surgery, he buys junk so she wont' lose weight. When she is admitted to the hospital some time later for heat stroke, Dr. Nowzaradan chastises her and talks about how dire her situation is, and sets Bettie Jo and her husband up with a counselor. There we learn that Bettie Jo has been the victim of several rapes prior to her tremendous weight gain, and to some degree she sees the weight as a protection against future sexual assaults, because men do not come near her in her overweight state.
Eventually BettieJo gets down to 440 pounds and goes to visit her family, and they notice her weight loss but are rather tepid in their responses - You look "OK" or "better". Then fill the table with fried unhealthy stuff, plus none of them look like they have missed any meals either.
So here you see many components of other 600 lb life stories - a person who has been sexually assaulted in the past and sees being morbidly obese as a protection against that, an enabling partner who does not really want the obese partner to be independent for fear of being abandoned, and a less than supportive family of origin. The one thing usually pushing the person towards losing the weight is the knowledge they will not live much longer at that weight. Dr. Now, as he is called, is firm but compassionate as usual.