Eating barley sugars in class has become a rite of passage for three generations of Australian youngsters.
World Vision's 40 Hour Famine clocks up its 40th anniversary this weekend.
The aid group's chief executive Tim Costello said the event had raised $200 million in Australia and saved the lives of tens of thousands of people.
"Ice bucket challenges and click activist campaigns come and go but 40 years on it's still as strong," he told AAP.
Mr Costello did the first 40 Hour Famine in 1975, as a Monash University law student, at the instigation of younger brother and future treasurer, Peter, who was a World Vision youth ambassador at the institution.
40 HOUR FAMINE FACTS
* More than half the schools in Australia have participated in the 40 Hour Famine at some point.
* Millions of Australians have participated.
* 20 countries and 400,000 young people take part each year.
* Australians and New Zealanders are the only 40 hour participants, other nations only do 30, 24, 20, 12 and 8 hour famines.
* Concept stemmed from a 17-year-old Canadian girl's efforts to help Ethiopians affected by famine in 1971.
* The fundraiser was featured on Neighbours in 1994 and Heartbreak High in 1997.
* Money raised helps people in extreme poverty living in Afghanistan, Angola, Bangladesh, Cambodia, Chile, China, East Timor, Ethiopia, India, Kenya, Laos, Malawi, Niger, Somalia, Sri Lanka, Sudan, Thailand, and Zimbabwe.
