Think about the last time you cooked for a group of people without knowing exactly how many would show up. Too little and someone goes hungry. Too much and it ends up in the bin. Now imagine that problem on a much larger scale, involving farms, factories, and canteens all over the world. At the heart of this problem is a mismatch between supply and demand. A farmer has more harvest than consumers want to eat, while caterers nearby buy food from all around the world, often preparing more meals than they can sell, to prevent disappointed consumers. Since food spoils, you cannot simply store it for later, and these mismatches lead to waste. With climate change making harvests less predictable and people’s eating habits changing constantly, these mismatches are getting harder to manage. As a result, roughly one-third of all produced food is never eaten across the food supply chain. This affects both costs and the environment, because all the investments, water, land, and energy that went into growing and preparing that food are wasted too. Throughout this research, we investigated how food companies can more flexibly adapt to these imbalances, by buying food locally, by using side streams or leftovers to make new products, or by preserving oversupplied products so they can be consumed later. To do this, we used mathematical optimisation models to calculate the best decisions amongst all possible options. We then fed these models data from a municipality, a vegetable processor, and a caterer, to explore practical strategies that make supply chains operate more sustainably. The first study looks at short food supply chains. We investigated how locations in a city could be supplied with food products from local farmers. The popular idea of using a central collection point sounds logical, but our analysis showed that it is not beneficial financially due to the low volumes. It is better to keep it simple and ship products directly from the farmers to the customers. Still, transportation remains relatively inefficient and is therefore quite expensive. A useful reality check for anyone planning to invest in food hubs. The second study focused on how vegetable crops could best be processed. We found that converting side streams into food products, such as using carrot tops for pesto, can improve profit, but does not always reduce environmental impacts, as processing can require a lot of energy. Recycling is therefore only sustainable if the saved impacts outweigh the additional transformation impacts. Finally, in the context of food catering, we found that leftover reuse can reduce costs and environmental impacts when flexible recipes are used. These are recipes where ingredients can be replaced by others, such as substituting pumpkin with sweet potato in a curry. Leftover meal components can then serve as alternatives to fresh ingredients in new meals, saving costs and reducing waste. Across all three studies, increased flexibility proved to be key. By building flexibility into product formulations, offering broader categories like “vegetable mix” instead of specifying exact ingredients, or allowing substitution through flexible recipes, companies can reduce overproduction and make better use of what is already available. There is no single magic fix for food waste, but small, smart changes in how we buy, process, and plan can make a difference.