The morbidly obese subject of TLC reality television show My 600-lb Life died filming an episode.
Robert Buchel, a 41-year-old who weighed over 380kg at the beginning of the season, passed away from a heart attack last November as he awaited potentially life-saving weight-loss surgery. The episode only went to air this week.
TLC says it is deeply saddened by Buchel's loss.
"We are grateful to his family who were gracious enough to let us continue to share his brave story with our viewers. Our thoughts and prayers are with them at this difficult time," it said in a statement.
Buchel struggled with his weight, along with depression and an addiction to pain killers. He had managed to lose more than 100kg before his death.
His fiance, Kathryn Lemanski, shared her pain in a touching Facebook post.
"He did not deserve to go this way and this was not his time... Rob had a hard life and in the last 2 months he finally had hope for the life he always wanted. This was a robbery beyond words," she wrote.
"A person like him should never have to die this way and certainly not this young and most definitely not when his life was about to begin."
Buchel is the first person to pass away on the series. Another star, Henry Foots, died in 2013 following his appearance.