The singer, who was once addicted to working out, only has water and other drinks for almost two days, and says it reduces inflammation, reports a section of the media.
The 33-year-old has taken a go ahead from her doctor friend for this fitness regime.
"I do it very safely by having a purposefully nutritious food day the day before and after. On the fast day, I drink high-grade electrolytes and a lot of water (plus tea and coffee).
Fasting is safe and beneficial unless you are diabetic or have serious health issues," she said.
Singer Ellie Goulding performs on stage during an event.
"I built my way up to 40-hour fasts over time (started with 12). Fasting from time to is a great way to give your digestive system a break. It helps blood sugar control, and helps fight inflammation - the mother of all health problems," added the singer.
Earlier this year, the "Love me like you do" hitmaker, who is spending her lockdown with husband Caspar Jopling, admitted that she had been skipping songwriting and recording sessions to hone her fitness.
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"I felt as though I did at one point have a gym addiction that was just not fun, I felt I had to go to the gym every single day," she said.