The 83-year-old says he hasn't consumed food or water for seven decades, and doctors in India are trying to learn his secrets, or prove once and for all that his 70-year fast has been nothing more than a lengthy hoax.
Jani -- who says he gets all of his sustenance from meditation -- has agreed to spend three weeks in a hospital in Ahmedabad where he'll be observed by a team of 30 doctors, monitored 24 hours a day by cameras, and subjected to tests studying his brain and heart activity.
"The observation from this study may throw light on human survival without food and water," researcher G. Ilavazahagan told SkyNews. "This may help in working out strategies for survival during natural calamities, extreme stressful conditions and extraterrestrial explorations, like future missions to the moon and Mars by the human race."
Jani's condition is so extraordinary, some military experts wonder if studying him might help them develop supersoldiers.
Since the experiment began on April 22, Jani reportedly hasn't had anything to eat or drink. He also hasn't been to the bathroom.
That apparently is par for the course for the yogi, who says he was blessed by a goddess when he was 8 years old and hasn't needed to consume food or water ever since.
In 2003, Jani -- who reportedly spends much of his time in a cave near a temple for the goddess Ambaji in India's Gujarat state -- underwent a 10-day medical observation, during which he didn't eat, drink, urinate or defecate, according to the BBC.
Although people can survive for several weeks without eating, most can only survive several days without water.
Prahlad Jani says there's no diet like no diet at all.