The former Take That star, who had been photographed earlier this week leaving a Greek restaurant in Malibu with a reported 'double-chin', uploaded a snap which showed him sticking his middle fingers up while looking toned and trim in his Los Angeles home.
The image was accompanied with a typically tongue-in-cheek tweet: "Thank you for your internationally syndicated horrid picture of me (the one you put up of me leaving Taverna Tony's...) Just to 'weigh' it up here's me at home the next day...
"With much love and respect, Robert."
The 38-year-old singer, who has been writing music with former X Factor finalist Craig Colton, confirmed late last year that he is working on a solo album following a deal with Universal.
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Watch the music video for Robbie Williams's 'Bodies' below: