Rishi Sunak fasts for 36 hours at the start of each week, it has emerged.

       The prime minister survives on a diet of water, tea or black coffee from 5pm on a Sunday afternoon to 5am on Tuesday morning, his friends say.

       One said: “He is incredibly disciplined.”

       A source close to the PM told The Sunday Times: “It’s true, he doesn’t eat anything at all on a Monday.

       “It’s remarkable really given that he is often on visits or doing PMQ prep on a Monday. It’s a real testament to the discipline, focus and determination that he shows in all aspects of his life and work.”

       Mr Sunak, 43, has spoken before about the practise – a key part of the Hindu religion – but the full extent of his fasting has not been revealed until now.

       He previously told how his morning routine consisted of an early rise and a gruelling Peloton workout, followed by either no breakfast at all or a small one, such as Greek yoghurt and blueberries.

       In an appearance on the Twenty Minute VS podcast last year, Mr Sunak revealed his preferred time to wake up in the morning is 6am.

       He said he is a “huge fan” of Peloton workouts, namely those led by Cody Rigsby, one of the brand’s most popular instructors and a huge fan of Britney Spears.

       “I’m a huge Cody Rigsby fan. He has been my long-term favourite, which means you do have to listen to a lot of Britney,” Mr Sunak said, adding: “But you know, no bad thing in trying to get you motivated, I guess.”

       When he is not taking part in a Peloton class, Mr Sunak opts for a run on the treadmill or a high-intensity interval training session at his local leisure centre.