How to eat healthy when others treat anything with nutritional like vampires do holy water?

Wow, I am so sorry that your parents aren't supportive of you in a nutritional way. Poor thing. Is your family overweight? Perhaps you need to see a doctor about your issues, get them to give you a report on the bad health issues that may arise from the diet that your family keeps, then show your mum the report. Maybe ask if you can go shopping with her too, and start picking out healthy foods and stopping so many unhealthy foods go into the shopping trolley. How old are you? If everything else fails, find a job that only gives you a few hours, that should be enough for you to purchase your own food.