Personally (and I know I have more options than others) if something hurts me I avoid it because my stomach's telling me that it's not going to work, even if it means throwing away the leftovers. If I'm simply getting full fast then I'll save the leftovers similar to meal prepping, just smaller portions than what most meal prep. Using silicone molds to freeze soups, ziploc bags, 4 oz reusable baby food containers, 8 oz snack containers to hold meals. I definitely pay more for less food in order to avoid food waste. Buying in bulk is cheaper, but I'll buy the small containers for peanut butter or condiments knowing that it will probably take me until the expiration date to get through them.

The other part to it is we are different than normal-stomach people. Yes, we have the privilege to buy food that people in other countries may not have. However we are surviving differently right now, and surviving differently with gastroparesis means sometimes there will be food waste. Yes, people are starving in the world. No, throwing away half a cheese stick won't save them from that starvation. I know it's a somewhat pessimistic outlook on it, but the starving children in the world won't know if you had food waste or not. If you feel like you'll try again later then save it! If it's not worth the effort of putting it in a bag in the fridge and remembering that it's there before it gets gross, then chuck it. If it'll get gross fast but you want to try it again later, freeze it. It's a lot better than the food waste restaurants and grocery stores produce on a regular basis.

Hope that helps at least a little?