Now, after huge pressure, these two big supermarket chains have started talks with food banks and charity groups about giving them food donations.
A group of seven students at Chinese University is also making an effort by limiting food waste and allocating resources to the needy.
"What you thought is rubbish is, in fact, a misplacement of resources," says 19-year-old Leticia Wong Man-huen, a Year-One student of journalism and communications, who is a member of the Facebook group called The Leftovers.
This group, which started this year, recruits volunteers to collect and redistribute edible leftovers to homeless people in the city.
"We hope to educate people, especially students, about the importance of thinking from the consumer's point of view," says another member, Olive Chu.
"If untouched dishes in banquets are re-distributed, the resources can be properly used."
The seven volunteers have gone out to various shops to collect their leftovers and send them to the homeless outside the Hong Kong Cultural Centre, in Tsim Sha Tsui. They have also been trying to work with secondary schools to collect their leftovers after graduation banquets.
Yet Wong says the task is challenging: although most schools choose to have buffets to offer a variety of foods, and there is always some untouched food left over, the caterers may not always allow guests to take food away.
This was certainly the case at Heep Yunn School. Sophia Leung Hiu-tung, a student at Heep Yunn, who tried to organise the collection of leftovers from her June graduation dinner, was unhappy when the InterContinental Grand Standford Hong Kong hotel did not allow people to take leftovers. "I was frustrated; we paid for the buffet, but the hotel forbade us to take any leftovers," she said. "I felt bad to see untouched food thrown in the bin."
Some of the leftover food placed in containers.
A hotel spokeswoman said that it did not allow leftovers to be donated because of food safety fears.
Robin Hwang - executive director of the Foodlink Foundation, Hong Kong's leading hunger relief charity, which collects surplus food from hotels and delivers it to the needy, confirmed this health concern.
She said: "Unlike the US and Canada, Hong Kong doesn't have the Good Samaritan Legislation. The policy protects the donors against any liability [if someone gets sick from eating donated food]. It's why hotels are unwilling."
Hwang also said that the food served at banquets is also harder to handle, since it will sit longer on the serving table and spoil more quickly.
"We work very closely with banquet managers. We discuss with them in advance about the types of food suitable to be collected and make decisions based on how the food is served and how long it'll be sitting there for," she says.
For more details go to Foodlink's website at www.foodlinkfoundation.org