Spencer Matthews has lost nearly two stone since June.
The 'Made in Chelsea' hunk has shed 25lbs since the end of the E4 reality show's fifth series after admitting he was "f***ing fat", and has urged his friends to tell him if he ever puts on weight again because he doesn't keep a check on how heavy he is.
He said: "Since the end of last series, I've lost 25lbs. I was so fat - I'm amazed that my mates didn't tell me.
"Weight creeps onto me, because I don't weigh myself regularly. One day, I'll just get out of bed, look in the mirror and I'm f***ing fat again!"
The 29-year-old star - who flaunted his new toned body before running The Blenheim Palace 10k in aid of the British Heart Foundation (BHF) on Sunday (06.10.13) - has appeared on the series since it first aired in May 2011 when he sported long hair, and admits he hates looking back on pictures of him with lengthy tresses and can't believe nobody told him he looked ridiculous.
He added: "Again, someone should have the foresight to tell you! Someone should just say, 'Mate, your hair looks absurd!'"
Spencer is set to cause controversy once again in Made in Chelsea's upcoming sixth series - which starts on Monday (14.10.13) - when he voices his support for ex-girlfriend Louise Thompson, which angers his other ex and co-star Lucy Watson.
The brunette beauty blasts: "You're standing up for Louise now? Literally go f**k yourself."
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