A health-conscious Santa is refusing to wear a pillow under his suit as he believes it promotes child obesity.
Bill Winton, 80, said children traditionally viewed Father Christmas as a chubby role model and grow up thinking it is fine to be overweight.
The former pipe coater said he was spurred into action after noticing children sitting on his knee had become heavier over the years.
The 12-stone Santa is at Westside Plaza Shopping Centre in Edinburgh.
Speaking to BBC Scotland news website, Mr Winton, from Wester Hailes, said he maintains a healthy diet and does not drink cola.
He said: "It makes me wonder why parents allow their children to get into that state and makes me slightly annoyed about it.
Bill discards the pillow to be thin Santa
"The parents and kids have been asking why I'm so thin and I say 'Santa's been on a diet' and everyone is in agreement that it is a good idea.
"I have always eaten healthily and have run a healthy eating course in the past. I gave up cola years ago when I saw what it did to a penny.
"I hope other Santas across the country follow suit so that parents start taking responsibility for their children's diets."
Alex Limond, Westside Plaza Shopping Centre, said: "We back Santa in the campaign to fight obesity in children, which is in the news and everyone's minds.
"It is time for a change and as Santa is a role model for children, then his body shape is where it should start."