How to make an actual impact?

Ever since I heard about the MASSIVE amounts of food this world wastes, I've tried to think of ways you can actually come together and stop people from throwing away food. Of course there are little things you can do: go door to door from little business to little business, collect food and give it to shelters or something of the sorts in your neighborhood. BUT a few people doing this on a tiny scale is not going to solve the problem from my point of view. Most food is thrown away before it even hits the supermarkets. Of course cutting down the waste after produce hits the shelf is essential to but what would be a good way/is it even possible to do something that handles the problem at the source?