The 20-year-old singer uploaded this rather buff photo of himself to Instagram on Tuesday night (30 July), admitting: "I never do this but... Healthy living and fitness update. Post workout picture. #diabeticinshape #2.O0."
Nick was diagnosed with Type 1 Diabetes in November 2005.
He might not usually post selfies like this but we're betting plenty of his female fans are rather glad he did.
Nick and band mates/brothers Kevin and Joe are currently on tour over in the US, with their next scheduled stop tonight in Raleigh, North Carolina.
TOWIE, celebrity babies, Mollie King: yesterday's headlines in pictures