Sir Paul McCartney lost 14lbs in one week after contracting a stomach bug.
The 72-year-old music icon was rushed to hospital in May during a trip to Japan, where he fell ill with the mystery sickness which resulted in him suffering dramatic weight loss.
Discussing the illness, he revealed: "It was some stomach thing and I was throwing up and didn’t eat for a week, which is one way to lose weight.
"That’s not recommended. I lost nearly a stone (14lbs) or something."
The former Beatles star – who is married to Nancy Shevell – was forced to cancel the remainder of his Asian tour but ultimately was glad he did because the time he spent resting made him feel "stronger than ever".
He added to the Daily Mirror newspaper: "My friends said, ‘Normally, you’d hate that because you love working.’ "
"But I took six weeks and came back stronger than ever."
Thankfully the illness was not life-threatening, and he praised doctors at Tokyo’s St Luke’s International Hospital who nursed him back to full health following the scare.
He said: "They looked after me amazingly and by then I was on the drugs anyway, so I didn’t care. I felt great."
Following the cancellation of several dates in the country, as well as one show in Seoul, South Korea, the ‘Hey Jude’ hitmaker has vowed to make it up to his Japanese fans and promised he would soon be returning to the country.
He said: "I’m going back to Japan next year."