A lot of jockeys struggle with their weight but Dean Yendall is an exception.

The natural lightweight started a diet on Tuesday morning to get down to ride Wandjina at 49.5kg in the Cox Plate.

After cutting back on chocolate and potato crisps, Yendall said he had lost 1kg and would have no trouble riding the Gai Waterhouse-trained three-year-old at the allotted weight.

Yendall drives countless hours to some far-flung Victorian country meetings from his home base at Horsham and resists the temptation of junk food during trips home.

He said he walks around comfortably at 50kg and can eat and drink whatever he likes, but steers away from fast food unless it's a last resort.

His weakness is chocolate and potato crisps but that temptation has to be put on hold as he goes about readying himself for the chance of a lifetime.

"It's going to be awesome, exciting times," Yendall said.

"I think the horse has got a chance with no weight on his back. He's drawn a nice enough barrier.

"Hopefully I can find a nice enough spot for him. There's going to be a fair enough tempo with The Cleaner but I don't think the boys will give him a picnic to cross over."

A win on Wandjina on Saturday will no doubt see Yendall come off the diet, but it won't be a big night as the jockey prefers water and soda water to wine and champagne these days.