Food waste is a problem, but among foods that are wasted, the environmental impacts of some are worse than others. One of the major problems with food waste is that all the resources and energy that go into creating food also are wasted if that food goes uneaten. So if you want to trim your food print, there are areas where your energies will have a bigger impact. The most significant is in the area of meat: while I won’t tell you to become vegetarian (though that could dramatically reduce your ecological footprint), changing your food and waste habits with regard to meat is an area of great potential. While animal products make up a smaller portion of household food waste, the environmental impact of those products are significantly higher. In many ways reducing food waste fits in with many other aspects of ethical eating (for instance local or organic foods may have lower footprints as they travel shorter distances and may use fewer inputs).
For more info on your food’s ecological footprint: