Here is the account of what truly happened in Erebor and the sad fate of Bombur
"Dwalin turned to Dori, a worried expression on his face.
'I fear that if this siege continues then we shall soon run out of supplies. All of our people are on short rations, yet still our stores run low.'
Dori frowned, seeing the truth of Dwalin's statement in his gaunt face and hollow cheeks. 'Friend Dwalin, there are few enough of us remaining, who journeyed to reclaim this Mountain from the fell Dragon Smaug. I will not allow us to come through so many hardships only to die of starvation while being beseiged by these accursed Easterlings!'
'But what can we do? No aid will come to us to help us break this siege, and our supplies will not increase in the storeroom.'
Dori looked at his friend, a sly look with barely concealed greed in his eyes. 'Well, I may have a solution to this predicament Dwalin. What say we go and see our good friend Bombur?'
A look of understanding crossed Dwalin's face.'That sounds like a grand idea my friend, lets do that.'
The pair walked through the great halls of Erebor, and found Bombur reclining on his sturdy sofa. Despite the recent food shortages, he was still enormously fat; his body was easily the size of both Dori and Dwalin together.
'Dwalin! Dori! My friends! Is it supper time already?' Bombur greeted them.
Dwalin and Dori glanced at each other, and behind their backs they tightened their grips on the knives and forks which they held.
'My friends?' said Bombur, a worried expression on his face. 'Why do you look at me so? You look almost like a pair of wolves advancing on a hopelessly snared rabbit....My friends.....'"
The rest i shall leave to your imagination