Queen Elizabeth might be a dream dinner party guest for many, but having Her Majesty over for a meal might be a royal pain given her family’s various dietary restrictions.

UK newspaper The Sun revealed what the royal family can and can’t eat when they’re out at a restaurant or travelling, and it seems luxuries like lobster and steak are off the menu.

Shellfish is the main food group the royal family is forbidden from consuming when they’re not eating at home, given its high risk of food poisoning.

With so many official commitments, Queen Elizabeth, Prince Phillip, Prince Charles, Prince William, Prince Harry and Princess Kate can’t afford to fall victim to an upset tummy.

They must also avoid rare meat and tap water when abroad.

According to The Sun, the Queen always sticks to the rules but some of her younger family members are more gung-ho.

During a tour of Canada in 2016, Princess Kate and Prince William broke with tradition to try raw geoduck, a type of clam native to the area.

Prince William and Princess Kate enjoy some clam sashimi in Canada. Photo: Getty

They also favour takeout, often ordering it to the palace.

During an interview with BBC Radio 1 in April this year, Kate and William said they liked to eat takeaway curries while watching box-set television.

“It doesn’t usually get ordered to the palace,” William explained. “We tend to pick it up [but] not ourselves.”

The Prince revealed he isn’t a huge fan of spicy food – “I’m not so good with it” – a trait he shares with his stepmother.

Camilla Parker Bowles, along with her husband Prince Charles, favours British food on the blander side.

The various diets of Britain’s royals have been the subject of plenty of gossip in recent months after rumours surfaced that the Queen enjoys up to four alcoholic drinks a day − two at lunch and two before bed.

But her former chef Darren McGrady told CNN while the Queen enjoys a tipple she would be “pickled” if she drank that much.

Instead, she stays fighting fit by keeping her nightly dinner simple when she’s at home, preferring grilled fish and salad over opulent degustation meals.

However, she’s never one to say no to chocolate.

“It has to be the dark chocolate, the darker the better,” McGrady revealed.

John Higgins, another former royal chef, told the National Post this year that Queen Elizabeth has also outlawed the use of garlic in the Buckingham Palace kitchens – possibly to decrease the risk of garlic breath during meet and greets with the public.