I would say don't ever touch meat, dairy, or overt oils to increase lifespan. You also want a BMI between about 18.5 and 22 and keep it there.
I'd try fasting longer if I were you. The health benefits can be remarkable. I don't know about once a week, Seifried's studies indicate a 7-10 day fast once a year, but those days need to be consecutive and preferably 10 days minimum and not 7.