A 12-year-old Texas girl who became morbidly obese after a rare illness triggered by brain surgery could get a potentially life-saving operation by February, thanks to a flood of donations from strangers.

More than 1,700 people have contributed more than $70,000 for Alexis Shapiro, of Cibolo, Texas, who weighs nearly 200 pounds and is gaining about 2 pounds a week because of a runaway condition called hypothalamic obesity.

That’s in addition to at least four anonymous philanthropists who have stepped forward to help. The response started within hours after NBC News first reported the story on Saturday.

“My goodness! It’s crazy,” said Jenny Shapiro, Alexis’ mother, who added that her family has been surprised and touched by the generosity. “Alexis really likes it. I think she feels like people aren’t looking at her anymore and people are rooting for her.”

Doctors say gastric bypass weight-loss surgery is the only thing that can help Alexis, but the U.S. military, which provides her family’s health insurance, says it won’t pay for the operation because Alexis is too young.

TRICARE and Humana Military, which provide family insurance for Alexis’ father, Air Force veteran Ian Shapiro, denied the request citing rules that say gastric bypass surgery may be covered, but only if the patient is 18 or has achieved full bone growth. Officials said the family could appeal the decision.

But Alexis’ parents — and doctors — say that an appeal could take too long and that there would be no guarantee the child would be approved for the $50,000 operation. Ian Shapiro, 34, is claims representative for USAA, a banking and insurance provider. Jenny Shapiro, 34, works part-time as a dog groomer at PetSmart.

“If nothing else, we have what’s required for the hospital,” Jenny Shapiro said. “If I need to make payments or whatever, then I will.”

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Dr. Thomas H. Inge, an expert in pediatric obesity at the Cincinnati Children’s Hospital Medical Center, said Alexis could receive the surgery at his hospital within six weeks now that the funding appears to be in place.

“The team is certainly in favor from a medical standpoint of moving forward as quickly as we can,” he said.

Every extra pound gained is a risk to Alexis, who has developed Type 2 diabetes and other health problems in the past two years. She was just 9 when she developed a benign brain tumor called a craniopharyngioma, which affects at most 1 child per every million per year.

Surgery to remove the tumor went well, but it damaged her hypothalamus and pituitary gland, two organs that help regulate energy balance, appetite and weight.

Like more than half of children who get those tumors, Alexis developed hyperphagia and hypothalamic obesity, disorders that make her gain massive amounts of weight — even as her body thinks it’s starving.

Her parents have had to monitor her food intake and exercise extremely closely, sometimes limiting the child to 900 calories a day. In the past, they’ve had to padlock the kitchen cupboards because Alexis’ conditions cause cravings that make her want to eat an entire jar of peanut butter at one sitting, for instance.

Gastric bypass surgery could help Alexis lose between 20 percent and 30 percent of her body mass, and also curb the misfire between her brain and gut that makes her feel like she’s starving, Inge said.

What’s not clear now is, even if the initial surgery is paid for, whether TRICARE would cover any follow-up care that Alexis might need. Officials with the military insurer did not respond to NBC News requests for comment about the new developments in Alexis’ case.

The Shapiros and Inge said they were planning to talk on Monday to discuss the timing for surgery — and its aftermath. Bariatric surgery is a serious procedure with lifelong consequences. New research by Inge and others suggests that teens do about as well as adults after weight-loss surgery, with the risk of major complications in about 5 percent to 7 percent of cases.

The money raised by NBC News readers and others will help pay for the surgery, Jenny Shapiro said. Any extra will go toward the costs of travel, lodging and other expenses as the family of five travels to Cincinnati for the operation. The family had started an account last summer at GoFundMe, one of several websites that help people raise money for medical expenses. Site organizers charge 5 percent of the donated amount, plus another 2.9 percent and 30 cents per transaction goes to WePay, a payment site.

But it wasn't until Alexis' situation received national attention that the fund jumped, within hours, from a little more than $1,000 to more than $50,000. As of Monday evening, it had grown to more than $71,000.

"I am really amazed at the power of information to bring out the best in people in cases like this," said Inge.

Alexis and her family are cheered by the outpouring of goodwill and generosity, especially during the holidays, Jenny Shapiro added.

“It’s going to be a lot of hard work,” she said. “We know that it’s not going to be 'Have the surgery and, yay, everything’s fixed.' But it’s a start.”

JoNel Aleccia is a senior health writer with NBC News. Reach her on Twitter at @JoNel_Aleccia or send her an email.