(CNN) She wanted to feel numb. She wanted to take back power over her own body. She wanted to be in control. So, she ate.

Then, she purged, and just like that, a self-destructive cycle of bulimia began in Sydney Fitzgibbons' life.

Fitzgibbons now describes herself as a passionate, resilient and kind-hearted 22-year-old with a strong sense of humor. Based in Denver, where she works as a paramedic, she can often be found riding a bike among the breathtaking blue spruce and ponderosa pine trees that adorn the Colorado landscape.

Yet, about three years ago, Fitzgibbons was just starting this chapter in her life, which follows chapters of pain, secrets and resilience.

When Fitzgibbons was a young child, growing up in Casa Grande, Arizona, she experienced sexual trauma, not at the hands of anyone directly in her family, she said, but by someone she knew and trusted.

After the traumatic experience, she turned to food for comfort, she said.

"It's always been clear to me how I developed an eating disorder," Fitzgibbons said. "I learned at a young age that even if you can control nothing else around you, you can control your own body."

"There is hope and life on the other side of an eating disorder," said Sydney Fitzgibbons, 22.

There were moments after Fitzgibbons would purge when she would sit on the cold bathroom floor, sweaty and dizzy, and think, " 'This can't be normal,' " she said. "The first time I felt significant heart palpitations, I finally admitted to myself, 'maybe this isn't just a diet gone wrong.' "

In 2014, Fitzgibbons was admitted to the Eating Recovery Center in Denver for treatment for bulimia for a second time, after multiple admissions to other treatment centers.

"I didn't even initially go for myself," she said of the recovery center. "I went because seeing the pain on my family's face was too great to deal with anymore. I went in for my parents, to save their daughter's life, and I came out with my life, Sydney's life."

While in treatment, Fitzgibbons said, she learned how she could feel anxiety or stress without using harmful behaviors to cope. Now, as a paramedic, she saves lives in the same city that saved her own life those few years ago.

Two separate studies on bulimia and the brain published in the Journal of Abnormal Psychology this month shed new light on the eating disorder, as it relates to feelings of acute stress and hunger or satiety

"I absolutely believe stress can be a trigger," said Fitzgibbons, who sits on the ambassador council of the Eating Recovery Center where she received treatment.

"Compulsive behaviors such as restricting, bingeing and purging, in my experience, have been almost always a way to manage overwhelming anxiety caused by stress," she said. "My eating disorder behaviors have often been a physical representation of my anxiety and stress when I didn't have words for what was going on in my life or what I was thinking."

The new studies, which involved magnetic resonance imaging or MRI, not only offer a better understanding of a patient's brain on bulimia, they may hold clues to improving treatment options in the future.

Currently, bulimia is treated with nutrition therapy, psychotherapy, nutritional counseling, support groups or medicines, such as Prozac, according to the US Department of Health and Human Services

Bulimia can be life-threatening, and seeking treatment is essential, said Allison Chase, executive director of the Eating Recovery Center in Austin, Texas, who was not involved in the new studies.

"Research has validated that there is a very strong relationship between bulimia and the brain, helping us to better understand that there is a strong biological basis for this disorder," Chase said, adding that environmental factors such as life events, relationships or stress can also play a role in an eating disorder.

"Due to the biological as well as environmental factors, it is a complex disorder that can be challenging to treat, but recovery is possible with the proper level of treatment and support," she said.

What happens in the bulimic brain when stressed

Researchers have long known that stress can play a key role in bulimia, but one of the new studies reveals how the bulimic brain may view food as an escape from that stress.

The brains of women with bulimia respond differently to images of food after a moment of stress than the brains of women without bulimia -- and the women may not even realize it, according to the small study.

Sarah Fischer, associate professor of psychology at George Mason University and a co-author of the study, is excited to share the new research with her clients, she said.

"I'm excited to share with them that there is potentially something going on in the brain that makes it more difficult for them to break this cycle of behavior, as opposed to feeling self-blame or that 'I don't have enough willpower,' " she said. "I would love to follow this research up to explore how we can use this information to develop more biologically informed treatments for bulimia."

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For the study, 10 women with bulimia and 10 women without eating disorders were shown a series of neutral images and food images while their whole brains were scanned in a MRI machine. Then, the women were asked to complete a questionnaire about their stress levels and food cravings.

Before the study, all participants were given a meal with the same amount of nutrients so that they were not feeling hungry, which could skew data, Fischer said.

Next, the women were asked to complete a series of simple math problems and then difficult math problems, and again were shown food images while their brains were scanned. Then, they were asked to complete a questionnaire about their stress levels and food cravings.

The complex math problems were intended to induce stress, as the participants were asked to complete them in a short amount of time while being given constant feedback that they were wrong and their data could not be used in the study if they got the math problems wrong, Fischer said.

While the researchers found that both groups of women reported the same feelings of stress and food cravings in the questionnaires, the MRI data revealed a different story.

The MRI images showed that women with bulimia had decreased blood flow in a part of the brain called the precuneus while viewing food images after completing the stressful math problems, whereas blood flow significantly increased in that part of the brain among women without bulimia.

The researchers replicated the same study in a different sample of 17 women with bulimia, this time focusing on the precuneus, and found the same results.

The precuneus is associated with self-perception and memory. For there to be less activity in that region among women with bulimia while viewing food images suggests that they may be using food to avoid thoughts about themselves -- especially after moments of stress, Fischer said.

However, more research is needed to determine whether the food images in the study -- or something else -- actually played a role in this self-distraction and decreased blood flow in the precuneus.

Although the research appears interesting and promising, it falls more into the category of a pilot study, and the results should be viewed with caution, said Dr. Guido Frank, an associate professor of psychiatry and neuroscience and associate director of the eating disorder program at the University of Colorado School of Medicine.

"The stress design is excellent. We know that stress triggers binge-eating episodes, and brain imaging can be a very useful tool," said Frank, who was not involved in the research.

Yet "the use of pictures is suboptimal, as it does not tell us anything about chemistry in the brain," he said of the study. "We do not know what causes bulimia nervosa; however, the repeated episodes of binge-eating and purging, self-induced vomiting, cause massive changes in brain chemicals."

Another issue with the study is its tiny sample size, Frank said. That was due to expenses, since each brain scan costs about $500, Fischer said.

All in all, "this was really exciting, because it is hard to replicate findings in clinical samples in neuroimaging," Fischer said of the study.

GET HELP Call the National Eating Disorders Association helpline: 1-800-931-2237

"In my clinical experience, clients with bulimia will say that their self-critical thoughts are extremely powerful and disruptive," she said, "and it is very easy to see how people distract themselves from these with behaviors."

That turned out to be a reality for Skylar Liberty Rose at a young age.

Bulimia 'thrives in isolation'

Rose now finds solace in her writing, photography and mindfulness, as well as candles, classical music and chai tea -- but she said it wasn't always that way.

Whenever the London native lacked control or felt stressed, she said, she would binge-eat whatever she wanted and then make herself sick and purge the food so that her body wouldn't take on extra pounds.

She started doing so when she was 18, living in the city and working as an administrative assistant. It made her feel powerful, she said.

"It was almost like, 'OK, I've got all of this stress, and I've got all of this anxiety, but this is my release,' " Rose said. "My state of mind was, 'if I'm stressed and overweight, that's way worse than being stressed and thin.' "

Around the same time she flirted with bingeing and purging, Rose also smoked, socially drank a lot and "never really viewed myself as having an eating disorder," she said.

"I wasn't really respecting my body in any capacity," Rose said, adding that she didn't even feel comfortable talking to her doctors about what she was doing. She was never medically diagnosed with an eating disorder.

"I was actually able to stay in a space of denial for quite a long time, because bulimia wasn't necessarily a part of my daily life. I would go stretches at a time without making myself sick, so I kind of normalized it," she said.

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Even though it happened only on occasion, it happened, and that was enough for Rose to eventually realize that she was harming herself and needed to change.

Between the time Rose was 18 and now, she has gotten married and divorced; was briefly hospitalized for pancreatitis; and traveled the world, "Eat Pray Love"-style, visiting Rome, India and Bali.

Also, "over time, I began to feel less inclined to punish myself that way, because, for example, I couldn't go to a yoga class and be really immersed in a spiritual and physical activity and then come away from that and hurt myself," Rose said of bulimia.

"I do view bulimia as self-harm, and I think that it tends to be something that really thrives in isolation," she said. "I couldn't physically be in a space of self-love at the same time as being in a space of self-hatred."

So "I stopped physically punishing myself, but I still felt the need to control, and I still felt anxiety around not being in control of every area of my life," said Rose, who is now 42 and living in New York as a writer.

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Rose replaced bulimia as a stress-coping mechanism with more healthful approaches, such as yoga, mindfulness and writing, she said. In 2015, she wrote about her experiences with bulimia in the Huffington Post

"It matters to me that it's spoken about," she said.

Though Rose no longer makes herself sick, she said, bulimia remains an ongoing battle. Without her new stress-coping tools in place, there could be a risk of relapsing.

"We don't just fix something once and then go through our lives and never need to have awareness about that thing again," she said. "So I see it as a continual journey that I take time to review and reflect on and make sure that I'm staying on track of who I am, make sure I'm making the best choices for me."

Making healthy food choices can be difficult for patients with bulimia; the other study published this week suggests that their brains respond differently to food rewards.

Bulimia's big unanswered question

The study involved 26 women with a history of bulimia and 22 women with no eating disorders, who had their brains scanned in MRI machines while they were given sugar water either after fasting for 16 hours or after eating a breakfast of bagels and cream cheese.

The researchers then analyzed the brain images to determine differences in how the women responded to the water's sweet taste when hungry or full.

The researchers found that the brains of women with no history of bulimia showed significantly more activity in the left putamen and amygdala when they were given sugar water after fasting, versus after they were fed.

Those parts of the brain are associated with evaluating rewards, such as how rewarding a taste is, said Alice Ely, a clinical psychologist at Christiana Care Health System in Delaware and lead author of the study.

As for the women with a history of bulimia, there was no such difference, and their left amygdalas had greater activity when fed compared with the other women -- which may hold clues to the binge-eating aspects of bulimia, the study suggests.

Ely, who was involved in the study while at the University of California, San Diego, likened the findings to grocery shopping.

"If you go grocery shopping when you're hungry, you're more likely to find everything look rewarding. We tend to buy more highly palatable foods," Ely said.

"If you go grocery shopping when you're full, you're not as interested, and you'll stick to your grocery list. You don't get pulled and motivated in a big way by a reward," she said. "Someone with bulimia, when their brains go to the metaphorical grocery store when they're full, they're still drawn to a sweet taste, even though they're full."

Limitations of the study include its small sample size, due to the high cost of brain imaging, and the fact that all of the participants with a history of bulimia were recovered or remitted from the disorder, Ely said.

"It would be important for us to test to see if this difference in response to taste existed or how it might present itself in someone who currently has bulimia," she said. Additionally, "we looked specifically at sweet taste, and we know that highly palpable foods come in many forms," such as high-fat types, too.

Still, no one knows whether bulimia causes such changes in the brain or whether such differences in the brain are associated with susceptibility to bulimia, Ely said.

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Dr. Walter Kaye, who led the study, hopes that that question could be answered as more research is conducted specifically on the brains of bulimics in the future.

"We really don't understand why people binge and purge. Clearly, stress and negative mood states are related to this. There's been this question about whether people restrict and get hungry and binge, or whether they just can't shut off eating once they start to eat," said Kaye, a professor and founder and director of the eating disorders program at the University of California, San Diego

"I have to tell you, human behavior is complicated enough that there may be more than one cause," he said.

As researchers continue to search for a cause, Fitzgibbons, the Eating Recovery Center ambassador in Denver, emphasized that healing is no mystery.

"No matter how hopeless life seems, there is hope and life on the other side of an eating disorder," she said. "Give recovery a true and honest effort. It is not a linear journey, so show yourself some grace and forgiveness in the process. ... Life gets better. Make sure you're there to see it."