Tree crops which produce carbohydrates, for example the oaks and aracarias, have higher per year productions year on year than any of the "conventional" grain or tuber sources including potatoes.
Granted the fact that these tree crops are not only approximately twice as nutritious by weight but also have a much better nutritional balance and one big aspect of food waste is immediately apparent.
Another aspect of the food waste is the energy inputs required to produce an annual crop as opposed to to a permanent tree crop. Tree crops are the least environmentally destructive and demanding of any cropping system and ironically the most productive.
Not to mention the bad diets and their implicit squandering of earthly resources. Food waste before food waste even starts.