Wisconsin-In three years, Lisa Brown has shrunk to just 77 pounds - after shedding half her body weight.

The 34-year-old former model is crippled by pain and a disease that is slowly starving her to death.

Strangers often assume that she has an eating disorder, but Lisa is actually the victim of a extremely rare condition - one of only 400 known cases in the world.

Lisa suffers from superior mesenteric artery syndrome (SMAS), a rare digestive system disorder where two arteries 'pinch' part of the small intestine called the duodenum, blocking food from getting through.

The disease means Lisa is unable to keep food down and, after three years of pain, she says she's now willing to let herself die. Lisa wasn't always a slave to her body. The 5'10" beauty from Wisconsin worked as model, went to college and graduate school, and got married.

But shortly after her 28th birthday, Lisa began to lose weight and couldn't figure out why.

Her clothing didn't fit her anymore, she was vomiting after every meal and suffering from severe stomach pain. When Lisa finally stepped on a scale, she weighed only 112 pounds - 33 pounds lighter than her normal weight of 145.

In 2013, Lisa received her diagnosis of SMAS after visiting three different hospitals, and going through a series of CT scans. SMAS is a rare and potentially life-threatening disorder that affects less than one percent of the population, leaving sufferers with a 30 percent chance of death. Often, diagnosis comes too late.

Lisa's weight continued to drop rapidly and the stares and comments from strangers increased.

She said: 'It never ceases to amaze me what people would come up to me and say.

'Once in the grocery store line, a person behind me asked my weight and told me that I can't starve myself because it doesn't look good.

'High school students yell at me to eat a cheeseburger when they see me in public.' 

By July 2015, she was down to just 89 pounds and unsure if she'd make it to her 33rd birthday.

Lisa was hooked up to a feeding tube for 16 hours a day to make sure she was receiving a proper amount of nutrients.

At the time, she described her chronic pain as feeling as though 'there are two metal fists grabbing as tight as possible and twisting my intestines'.

She said: 'The disease has taken everything.

'Time spent with family used to be recreational and fun - the more ill I became with SMAS, the more those things came to a halt and it transformed into a caretaker role.'

To spread awareness about the debilitating syndrome, she created a YouTube video entitled Be Brave SMAS Warriors.

The video made its way to specialists at the Cleveland Clinic. Lisa relocated there with her mother, Patricia Neuhauser, in May 2015.

Lisa was hooked up to a feeding device for 20 hours a day before a series of tests diagnosed her with gastroparesis, a condition that prevents the stomach from emptying properly.

Six months later, the hospital told Lisa she needed an intestinal transplant. Insurance, however, wouldn't cover the costly bill of an estimated $1 million.

It was something Lisa says she thinks would have worked.

'It was my last chance at surviving. But it didn't happen. It was way too expensive to do on our own,' she told PEOPLE.

Lisa and her husband Patrick left the Cleveland Clinic and, in May 2016, flew to Jackson Memorial Hospital in Miami, Florida - one of the few hospitals in the country that offers the transplant.

Lisa said: 'I was really deteriorating at that point and they told me I had to gain 20 pounds to have the surgery.

'I knew then and there I had no shot. I couldn't take it anymore.'

Patrick went on medical leave from his job in December without pay to be with Lisa.

He's also created a GoFundMe page to help cover the costs of Lisa's medical expenses. So far, almost $17,000 have been raised out of the $50,000 goal.

He told PEOPLE: 'The hardest part is just sitting here watching her suffer. But I promised her sickness and in health. I was just hoping for the health.'

After another care center told Lisa she wasn't a candidate for further treatment, and so Lisa finally moved into hospice care.

She said: 'It's not a scary thing. It doesn't mean you're ready for death. It means you're finding another way to help your fight.

'It doesn't mean you're giving up. I've never given up.'

On a recent outing, Lisa's mother took her to get her nails done. Lisa chose purple, the color for SMAS Awareness Day, which is January 28.

In a Facebook post afterwards, she wrote: 'It is rare I have the strength to leave the house lately, but mom took me out for this special manicure for a gift.

'Each day is more of a challenge for me as my body protests every intervention, but it is things like this that lift my spirits to fight another day.'