Bennett, who was known for being a virgin on the show in last year's season, took to his Youtube channel No Going Back to explain the diet and workout routine that helped him overcome being "weak and powerless".
Bennett described himself as a "pale, weak, frail and pasty kid" who was an "easy target for bullies."
"What made matters worse was that I was an easy target for bullies. I was small, I was weak. I wasn't able to stand up for myself. I had no self confidence. And to top it all off, one of my best friends would call me shrimp and pipsqueak and runt daily," Bennett explains.
"I hated it, I was tired of feeling weak and powerless. The feeling that I didn't matter, that I wasn't important, that there was something less about me because I was small."
His transformation has been 13 years in the making, using "trial and error" to find out what works for his body shape. In college, Bennett turned to compound lifts, where he saw his biggest improvements.
While he admits he's no "body builder" or "fitness model," his results are impressive nonetheless.
Although his time in the gym has seen him get stronger, he's also recognised the importance of nutrition. At first, he thought protein shakes would be the secret to gaining mass but he slowly realised that nutritious foods would have a greater effect on his body.
Looking back at himself, he jokes that he was a "50kg male who looks like he could get blown over in a stiff breeze."
You can watch the full video below.