Andrew McSherry, 52, said: “I did give up for a few months but I just couldn’t live without it.
“I shouldn’t drink it. The doctors have told me not to but I just can’t help it.
“My wife’s always moaning at me but there are worse things to be addicted to.
“I’m amazed I haven’t turned orange.”
When his addiction was at its worst in 2011, Andrew, of Cumbernauld, near Glasgow, was swallowing the equivalent of 150 teaspoons of sugar a day. He now drinks four litres of diet Irn-Bru every day.
Makers AG Barr said: “We would never advocate the over-consumption of any one product.”