In her new book, “Just Three Words,” 54-year-old triathlon champion and registered dietitian Karen Newman writes about overcoming cancer and beating bulimia while remaining a top competitor on the racing circuit. Here, the South Burlington, Vt., resident tells Michael Kaplan how cancer provided her with an unexpected and much-needed lifeline.

Cancer was an enormous blessing. It saved my life. That may sound crazy, but it’s true. The disease taught me that our greatest trials can be our greatest opportunities for growing and finding purpose.

When the doctor diagnosed me with Stage 3 breast cancer in March 2008, I was 46 years old and told that I had a 10 percent or less chance of living if I did not begin treatment immediately. I knew I needed to do it — I wanted to beat cancer.

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But I had a secret that I could not share with anyone. I had been living a huge lie: While traveling around the United States, lecturing people on nutrition and talking about being a top-10 triathlete, I routinely had bile on my tongue. Literally. I struggled with bulimia, making myself sick eight to 10 times per day — to the point where I was throwing up blood — and I was too ashamed to admit it.

My eating disorder began during sophomore year of college when somebody told me the secret of being able to eat whatever I wanted: Just throw it up. I binged on bagels, ice cream, waffles, cake. It all went down my throat and came right back out. Soon there was a voice in my head that I called the TaskMaster, the SlaveMaster, the Liar, the Deceiver. It would tell me, “You’re worthless, you’re fat, you might as well be dead.” That voice commanded me to throw up and I rationalized bulimia as the only way to stay thin. But it also became an escape from feeling inadequate. Vomiting gave me an endorphin chemical reaction. I lived on the high for a few seconds and then felt terrible again.

I stopped throwing up when I was pregnant — I felt responsible for the life inside me — but after my three sons were born I went back to it. It became like a drug — even while I worked as a dietitian and ran triathlons. At night, while everyone in the house slept, I went in the kitchen and binged. I got so good at vomiting that sometimes I could do it without my fingers.

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