Jack's version of events is that she had severe anorexia as a teenager. She recovered when she joined the fire service and started benchpressing monarchs, then she got pregnant and that fully cured her.
A lot of women who have had EDs actually relapae around pregnancy/childbirth - your body may not feel like your own anymore, you experience a major loss of control, and then there are the complexities of PPD etc. This is an area of healthcare that's been criminally neglected because women's health usually is, but pregnancy is a time when women are very vulnerable to MH issues, especially if they have a history already (severe anorexia), and especially if they spend their pregnancy suffering DV at the hands of an abusive partner, as Jack has claimed. Despite all of this, Jack's pregnancy marked the end of her severe anorexia.
Literal starvation would probably also cause a relapse in someone who has had an ED. Fortunately there is very little research in this area (fortunately because it's such a rare situation), but the Minnesota Starvation Experiment showed that patients with an extreme calorie deficit started to exhibit ED behaviour. If Jack were literally starving, and if Jack had previously suffered from anorexia, she would likely have relapsed...but by all accounts, she didn't.
TLDR: Jack lies about having anorexia. Jack lies about being starving. Jack lies about having a toaster FFS!
Yes to all you said, and also Jack said she had severe anorexia for 10 years, the implication being it started at grammar school. So even assuming early onset at 11 (rare) she'd still have it at 21, which then crosses over into the fire service, during which she could also apparently carry 3 men on her shoulders (unlikely with severe ED) and also the pregnancy, after which she started starving 'for real' due to material poverty. As you imply, NONE of it makes any sense at all and not much of it rings true. I absolutely believe she has / had an ED as she exhibits some of the behaviours, but not in the way she claims and it doesn't fit with the other things she claims in the same timeline.