A: Your family's sabotaging behaviors are about their own stuff, not about you. We don't know what goes on in other people's heads, but what you're talking about is very common among people who are trying to make changes in their life.
It also might sometimes be a misunderstanding. Here's how to address the issue in a non-confrontational way that gets your point across while maintaining (and maybe even improving) the relationship:
1. Let them know you see their perspective.
2. Specify exactly what behavior needs to change
3. Tell them how their behavior makes you feel.
4. Clarify why it is important for them to honor your request.
5. Clearly state what you need them to do.
Here's an example of this put into action:
Mom, I know it's disappointing to you when I don't eat some of the dessert you made (1). When you criticize me and minimize my goals (2), it makes me feel unloved and unsupported (3). I want to look forward to coming over to visit (4) and so I need you to respect my efforts to improve my health by not pressuring me about my food choices (5).
These can be uncomfortable conversations to have with your friends and family but the serious and straightforward approach you take will help communicate to them just how important it is to you that they respect your boundaries.