MIAMI ( – Gastric bypass surgery is often a last resort for the obese to save their lives. But a 443-pound man recently decided to have the life-changing surgery not to save his life, but to save his sister’s life.

Michael Torres’ story started with a bad car accident that made it painful for him to walk. After that, the weight just began piling up.

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“I went from a 143 pounds to 325 pounds in a span of a year and half,” Torres said.

He tried dieting, but for every 30 pounds he lost; he put on another 80. He had become trapped in his home, unable to even bathe himself without the help of family. Torres actually chuckles about it now, “They would say ‘Jesus, like bathing a Mack truck.’”

Everything changed though when his twin sister Ana was diagnosed with lymphoma. She was literally on her death bed three months ago when doctors discovered Michael’s stem cells were an exact match. The news brought her back to life.

“I was like, can’t begin to tell you,” Marin told CBS4’s David Sutta as she started to cry.

But, no one would draw Michael’s stem cells because of his weight. The strain on his heart could kill him.

“The doctor said there was no way he was going to take the chance unless I lost some weight,” Torres explained.

One doctor agreed to help Torres do that quickly. “It was the right thing to do,” Doctor Jorge Robazza told CBS4. Dr. Robazza moved up what is typically a year-and-a-half process to one month because he knew time was limited.

“This man right here not only saved my life but he saved my sisters life too,” Torres explained.

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A week out of surgery Torres is on his way.

“Before, I couldn’t even touch my hair,” Torres said. “I washed my own hair today for the first time.”

In the end it took saving his sister’s life to save his own.

“Whenever he’s ready, my body is ready for him to take his stem cells,” Marin said. “We didn’t come this long way for nothing. You are going to be skinny. And we are going to be running around and were going to be having a good time.”

The doctor estimates Michael will lose about 100 pounds in the next three months. After that he should be clear to have the surgery.

Now, as Michael Torres walks down the hallway at South Miami Hospital; his twin sister just marvels. “Wow look at you walk,” Ana Marin tells him.

“This is the most I’ve walked in months,” Torres told CBS4. He wasn’t all this way.

Doctors are still amazed at Ana’s progress. Since March, she went from dying to being virtually cancer free.

“All along I knew I was going to be fine. I didn’t know how. I just knew I was,” Marin said.

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Ana still needs Michael’s stem cells, but with those stem cells, it will bring both of them the gift of good health.