The Queen is a "chocoholic", according to her former chef.
Darren McGrady said the head of the Royal Family regularly ate chocolate cake with her daily afternoon tea but managed to stay in shape by having small portions.
And while the Queen was not a fan of garlic, her husband, the Duke of Edinburgh "loved" the strong-flavoured vegetable, he said.
Darren said: "The Queen loves chocolate. She's a chocoholic.
"I think for Her Majesty it's about small portions. She's very disciplined. So a tiny piece of chocolate cake and then back to the kitchen.
"The chocolate biscuit cake goes out again and again and again until it's all gone. It's the Queen's favourite but also William's favourite too.
"The Queen would take a mental picture of the chocolate cake and if any of it was gone, she'd actually ask; 'Who's been eating the chocolate biscuit cake?'
"One of the things we couldn't use on the menu was garlic. The Queen doesn't like garlic. It's an old Victorian thing, the after-taste of the garlic.
"We never used garlic when the Queen was at the table. But Prince Philip loved it, so when the Queen wasn't there we could use it."
Darren, who was personal chef to the Queen, Diana, Princess of Wales, and Princes William and Harry for 15 years, is serving food enjoyed by the royal family to some 600 guests at the Britweek gala in Los Angeles on Sunday.
He will make a chocolate cake he used to produce for the Queen on her birthday, using a recipe from Queen Victoria's era, and Diana's favourite dessert, bread and butter pudding.
The chef, who used to peel carrots for the Queen's horses, said Diana used to "really spoil" her children when they wanted certain foods.
He said: "The nanny would be up in the nursery and say; 'No dessert unless you eat all the main course.'
"Whereas Princess Diana would say; 'Yes, go on, eat it. You can have what you want.'
"I can see William and Kate spoiling George and Charlotte."