Maybe one way around dealing with family members who nearly force/wheedle unhealthy food that you don't like, is to do the reverse compliment:

Ask that they make a dish that you do LOVE/enjoy. That's how I dealt with my mother piling on tons of food for me whenever I visited her. I didn't want her to spend more money preparing food care pkgs., when I was earning an income myself.

So I pointed out a few favourites, foods that I don't prepare myself but they are my mother's specialty and I enjoy eating it later/or there at their home.

This tactic might not work if a family member eats too many different types of unhealthy food. Fortunately it's not the case for us, there is choice.