Isn't it awful that some of us have to constantly battle back against people who think they know us better than we know ourselves??
In the beginning I tried the polite "no, I'm good." or "no, it's ok. I'm so full, maybe later." or something to that effect and try to change the subject.
Now the gloves are off.
I specifically spell it out for them that I can't be trusted with "just one" and that my health and diet literally depend on me being cognizant of everything I choose to eat or drink. Having said that, it doesn't mean that I don't indulge here or there. But now, it's on my terms and what *I* choose to have, not the pressure from others.
It took me a long time to get here but I'm so glad I did. And it's actually easier than I thought and not as harsh as I might have made it sound above. It's just firm and confident speaking (even if I'm not exactly feeling firm and confident...).