Slimming World groups from across the borough are joining together to raise money for Cancer Research.
Men and women who have lost weight will be publically donating clothes that they are now too large for them to the charity.
Group leaders are also asking for people to join in and donate their own clothes and bric-a-brac.
They will be collecting goods between 12pm and 4pm in Walthamstow Town Square.
Items will be distributed to Cancer Research charity shops across the UK.