I think its PC nonsense about not reheating food or not eating leftovers. It's the same as the so called use by date on products I ignore it and go by look , smell and taste.
I rarely throw anything away either, although I have when it's been forgotten about.
If leftovers is food that is not cooked on the same day then I eat that everyday. My main food is Bangladeshi, mainly curries. There is always curry left over, always enough for meals the next day. The pot stays in a pantry or anywhere cool, then it is heated on The stove and I actually think it can taste better with age. all bangla families I know do this it's the norm.
rice is also always left over nowadays it's heated in the microwave, sprinkled with a bit of water and heat, it tastes as good as new. I'm shocked on the advice about not reheating rice. It's bull rice is my staple food. If it's not yours you may get an upset stomach intially but believe me it won't last. A better way of reheating old rice is in a colander with hot water underneath, it takes longer but it makes the rice a softer. This has been abandoned by most except the old fashioned folks.
curry can be freshend up by frying it like a stirs fry with birds eye dried chillies in some ghee butter, lots of garlic . Kids fight for here left overs it's got a char grilled taste.
Just had spaghetti bolognese from yesterday. The meat mixture is from yesterday but the spag is boiled new, I don't see the issue.
What about cheese that's a bit mouldy do u cut and use or throw away. I always use it
I think it's disgusting if people are throwing away a lot of food. We have become a nation of ungrateful gluttons. We over eat here in the west whilst people our neighbours and those abroad are dying from a lack of food.
That's my mantra any time I think I throwing food away, and it's what I drum into my kids when they say I'll eat what's on this half of my plate but not the other half.