After switching to a healthy diet and gradually introducing exercise into his lifestyle, John Burton lost 260Ibs in three years.
The 27-year-old from Manchester, who became a postdoctoral researcher after gaining an astronomy PhD in 2013, shared his incredible story on Reddit.
In 2008 when he was at his heaviest, Burton weighed 420Ibs. Today he weighs 160lbs, but some of that weight is due to the fact that he's been left with excess skin.
Burton uploaded a series of images of his body to Reddit and Imgur, explaining that when he has his shirt on, no one is aware of the excess skin and tissue he conceals underneath.
But when he removes his shirt, it is clear Burton has excess skin that is particularly noticeable around his stomach and arm areas.
He estimates that this skin and tissue weighs around 20Ibs.
Writing in a separate Reddit post, Burton says he used to hate his excess skin.
"Whenever anyone says how good I look, or how good I must feel, I put a face on and laugh, agree, maybe make a joke about how big I was. But I don't see the change," he says.
"All I see is skin. And I hate it. It's a constant reminder of who I was, what I did to myself. It didn't let me think that I'd changed. I still saw myself just as fat, just as worthless, just the same. Until very recently, that was how I felt."
Burton goes on to explain that he recently had "a moment of clarity" when speaking to friends and family, which has helped him to accept and even feel proud of his body.
"Rather than seeing it as a mark of failure, talking to some people in my life who made me see things in a different way, it changed me. It's not a failure...it's a success," he writes.
"And I may not love how I look, but fucking hell I'm not going to let it control me. I'm proud of what I've done, proud of the struggle and the effort and the toil."
Support for Burton has flooded in on Reddit, with many users telling him how great he looks. Several people have also offered to set up GoFundMe and Kickstarter pages to pay for skin removal surgery.
But Burton has declined all offers, replying: "I don't think I'd want money donated for me. Don't get me wrong, if people were willing to donate to help me, I'd be utterly blown away, more than I could ever say.
"I'd much rather a charity benefited from it though. If some good could come from it for someone less fortunate, that's the absolute ideal."