Impact of food waste campaigns muted, but point toward right direction -- ScienceDaily
They did a study at two univerity dining halls. Our local university in Germany was also for some meals a take as many as you want food, but to fight food waste they rely both on posters etc. about food waste and they provide portions/ready made plates. In practice this means there is someone behind the counter who puts the main dish on your plate. In addtion, you can get pre portioned bowls of various side dish. Still there is some food waste, but I think it helped a lot to reduce it.
Food waste campaigns are a low-cost way to curb waste at all-you-can-eat dining establishments, but they may need to be combined with other environmental changes to make a difference, says new research.