How can I get my father to eat healthier?
If you are the cook for the household, you can make healthier foods available, such as raw fruits and vegetables, rather than fatty snacks. Also if you prepare meals for you and your father, you again have control of the foods offered for dinner. Make more chicken and fish meals with appealing side dishes which are low fat, low sodium, etc.
Your Dad sounds like a sharp cookie and may not easily be tricked into eating healthy. I always try to eat frozen yogurt or "no sugar added" ice cream, when I buy frozen treats. My family eats these and doesn't notice a difference, and of course I don't tell them the real truth.