The 33-year-old actress was unable to walk for several months after the shocking accident when she was 17, but it gave her a "sense of purpose" to overcome her eating disorder.
She said: "I only modelled for a while and then I got hit by a car and ended up in a wheelchair, which probably actually saved my life. Otherwise, I would probably still be a model with an eating disorder...
"I got hit by one car into another car and basically destroyed my back. I was in bed for about a year and in a wheelchair for about six months after that.
"At that point, I had gained about 70 pounds on steroids, so I was 'too big' for modelling.
"I also developed a sense of purpose to protect my body after that and stop starving myself. I still had an eating disorder mentality, but I stopped actively starving myself once I got better because I realised that my body was fragile and I was taking it for granted.
"This was when I was 17. Very intense, but it saved my life."
The 'Good Place' star recalled the extreme measures she was encouraged to take to stay slim when she was modelling.
She told America's Cosmopolitan magazine: "I was encouraged to smoke by agents and peers.
"I was encouraged to only eat red peppers or take a small bag of sweetener around with me so that whenever I felt like I was gonna faint, I would just have a little bit of sugar rather than eat any full meals."
Jameela is known for her outspoken views and I Weigh body positivity campaign and she admitted she's turned down over $3 million in advertising deals over the last year because she didn't agree with the "messaging" of the companies.
She said: "I find the messaging of some brands, especially the ones targeted toward women, highly problematic and I can't work with those companies.
"I turned down maybe $3 million in the last year as my profile has risen. That's not even counting all the diet and detox brands, exercise DVDs, and fitness programmes I've been encouraged to sell, which push that 'fat is failure'.
"I would own about three houses right now if I gave them my time. I don't take them because I genuinely walk the walk about caring about the items that I'm promoting and encouraging other people to engage in."