In laws Stubbornness

Currently living with in laws but will be moving out soon. How do you deal with stubborn in laws who have health problems like high blood pressure, high blood sugar etc but never listen? I have been warning them to watch what they eat (less sodium - don’t take the gravy or soup when eating out), drink more water and stop drinking sugary drinks, avoid pastry and start exercising etc. I also told them the consequences if their health fails. One of them already had stroke before and cannot afford to have anything happens again. However, they still seem to be quite stubborn and always tell me “only once in awhile” (but actually it’s every few days) when eating oily, heavily flavoured and fried food just because they can no longer take plain food taste. They still add sugar to their drinks daily and barely drink a few cups of water a day. I do not understand how they can not learn when one of them already had health failure before. They are only in their mid 50s and I feel they are too young for these health issues. Part of me don’t want to care anymore because I am tired of nagging at them daily, and currently in trimester 3 giving birth soon. I would have no time to care for them once my baby is out. I should be glad that I am moving out soon, but another part of me feel quite worrying because they are my husband’s parents and I feel that I need to play a part in taking care of them. My husband already wants to give up because they never listen. I don’t know what to do to make them listen and be less stubborn.