Ellie Goulding says she fasts for up to 40 hours at a time.
The fitness fanatic only has water and other drinks for almost two days.
She claims it reduces inflammation and helps her digestive system.
But Ellie, 33, told worried fans the extreme measures have medical approval.
That's because she sought advice from a doctor friend.
She added: "I do it very safely by having a purposefully nutritious food day the day before and after."
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Ellie confessed she used to be "a gym addict".
However, she said it was no fun as she felt as if she had to go to the gym every day.
That might have been "a survival thing", she added, as touring can be tough and tiring unless you are very fit.
Building up to fasting
Instead, she now uses the fasting method to stay in shape.
And she claims it helps her digestive system to take a break.
Other benefits include blood sugar control, and a way of combating inflammation.
“On the fast day, I drink high-grade electrolytes and a LOT of water (plus tea and coffee)," she said.
Safe and beneficial
"Fasting is safe and beneficial unless you are diabetic or have serious health issues," she told The Sun.
Plus, she says she builds up to the 40-hour fasting sessions.
Firstly, she starts with smaller breaks in eating.
These can be as short as 12 hours long.
"Fasting from time to time is a great way to give your digestive system a break," she added.
It has given Ellie a break from compulsive exercising.
She said she realised she had a problem with working out when she started to skip writing sessions to go to the gym.
Her fourth album is expected out later this year.
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