Buchel suffered a heart attack and was 41-years-old.
Buchel's episode, which aired on Wednesday, included an epilogue from his fiancée
'I hate that this is our life and that this is Rob’s life but nothing stops him from eating,' she said during the episode.
'Food is killing him and taking our future.'
Robert, who weighed as much as 382kgs had lost more than 90 of those kilos at a Houston hospital in preparation for lymphedema removal surgery.
The New York Daily News reports after his first surgery, Bushel became addicted to pain killers and ripped out his stitches in an effort to get his hands on more pain drugs.
A spokesperson from TLC said the network was saddened by the loss of Robert.
'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,' the statement read.
Our thoughts are with Robert's family and friends.