Queen Elizabeth II
Queen Elizabeth II joked about fitness levels of rugby stars. Pictured: Queen Elizabeth II is seen at the Chichester Theatre while visiting West Sussex on Nov. 30, 2017 in Chichester, United Kingdom. Getty Images/Stuart C. Wilson

Queen Elizabeth II joked about fitness with her rugby star guests.

On Wednesday, the monarch hosted a Commonwealth reception at the Buckingham Palace. Prince Charles and Camilla Parker Bowles were in attendance along with rugby star brothers Billy Vunipola and Mako Vunipola.

During the gathering, Her Majesty reportedly joked about the fitness levels of the UK players. It was widely viewed that rugby sportsmen were tougher and fitter, but the queen seemed not to agree with it.

"She was saying that apparently rugby is getting a lot tougher now, everyone's fitter but she can't see it," Mako said (via The Telegraph). "I think she was calling us fat - which is fair enough."

Mako's brother who missed out on Six Nations rugby due to a broken forearm was very pleased that they were invited to the royal event. "It's a massive honour that we are here and a privilege, something we will probably brag to our mum about," Billy said.

The Vunipola brothers were born in Australia and New Zealand. Both are now playing for England Rugby. During the reception, Prince Charles approached the two athletes and chatted with them.

According to The Telegraph, the event signifies the start of a series of major Commonwealth events that will culminate in a heads of government meeting for global leaders in London in April. Queen Elizabeth II is the head of Commonwealth and there are rumors that the high-level leaders have been talking about her potential successor already.

However, the Commonwealth Secretariat denied those reports. The Commonwealth officials met "discussing the scope of the group's work and the areas of governance it will examine over the coming months," the Commonwealth Secretariat said in a statement. But "the issue of succession of the Head of the Commonwealth is not part of the group's mandate."

Prince Charles will be taking over the throne when Queen Elizabeth II dies. But the head of Commonwealth title will not be automatically given to him. However, chances are high that the Prince of Wales will have the position.

The former Prime Ministers of Canada and New Zealand, Stephen Harper and John Key, support Prince Charles for the title. In addition, the queen also hinted that her eldest son should succeed the title.

In 2015, Queen Elizabeth II showed up in Malta and said she could not "wish to have been better supported and represented in the Commonwealth than by The Prince of Wales who continues to give so much to it with great distinction."