For most people, the "beer belly" is caused by packing on too much weight. In the case of Hector Hernandez, it was because of a 77-pound tumor discovered in the back of his abdomen.

Hernandez said he had always considered himself a big guy. Before visiting a doctor, he went on a plant-based diet hoping to lose weight.

There was one problem: he lost weight everywhere except his stomach.

"I was basically like a thin person who’s got a huge belly," Hernandez said in an interview with USA TODAY.

In 2006, he visited a doctor and noted the unusual size of his stomach. Hernandez said the doctor told him it was because people gain weight differently. In his case, according to the doctor, it went straight to his stomach. "I left it at that."

Earlier this year, the 47-year-old California resident saw a new doctor after switching insurance. Because he had been diagnosed with high blood pressure and diabetes, he wanted a checkup.

The moment the doctor walked in for the first visit, it was clear how urgent Hernandez' case had become. "He didn’t introduce himself or anything, he just said 'oh my God, how long have you been like that,' and he touched my stomach," said Hernandez.

After seeing several specialists, Hernandez was diagnosed with liposarcoma, a rare type of cancer starting in the fat cells.

Dr. William Tseng, MD, a sarcoma expert at the Keck School of Medicine of the University of Southern California and Hernandez' surgeon, said sarcomas in general represent about one percent of all cancers, with liposarcoma representing a subset of those tumors.

"It’s essentially a fat cancer," said Tseng during an interview.

Tseng said one of the complications of dealing with sarcomas is symptoms don't appear as severe. Hernandez said he suffered heartburn, but figured it wasn't anything unusual. He also noted shortness of breath.

Another complication: how connected the sarcoma is to the rest of the body. "Over time, the organs get pushed out of the way, or the tumor surrounds the organs, but doesn’t necessarily invade them," said Tseng.

After a six-hour surgery in July, a 77-pound tumor — roughly the size of a 10-year-old child — was safely removed from the back of Hernandez' abdomen.

Since then, Hernandez said he is "much healthier now." He must return for followup CT scans every four months to make sure the tumor doesn't return, and continue those for a few years. His heartburn is now gone, and so is his high blood pressure.

"There’s so much i can do now that i couldn’t do before," he said. "I feel like a different person."

A GoFundMe page has since been created to help Hernandez pay for his medical bills.

Follow Brett Molina on Twitter: @brettmolina23.