ANSWER:

What she is doing is totally wrong because Allah has ordered us not to harm ourselves or others and by doing what she is doing, she’s jeopardising everyone’s health. 

QUESTION: Sheikh my mum thinks wasting single grain of food is haraam and hence she says we will b questioned abt every single food, she use the same oil ten times for frying, even she will use the black oil for cooking knowing the harm of it. She will even overeat the remain good food. Please help how to get rid to such kind of mentality? And is this rite that allah will punish for wasting or throwing food