Question: How do you turn down free food or treats for someone's birthday/an office party/something thoughtfully homemade just for you when you are on a diet? How do you do it without offending the baker or the person of honor and without looking like a snob?

I'm
not fat, but I am trying to fit into a wedding dress that was made quite snugly to begin with and things like
The Donut Vault keep coming up. What to do!?