Particular diet

Paddlefisher

So, I know once hubby & I announce, my awesome aunt & sister-like cousin will want to throw a shower. They're great people.  Only problem is: I am on a really specific diet - basically low carbs for the health of the baby.  Aunt & cousin are really into carbs and of course all baby showers have punch and cake, right??  I don't want to dictate the menu, but I do need to eat regularly and have no intention of eating cake or eating juice/punch. For dessert, I could have berries.  Plain.  Mose people want cake when they go to a shower, and no doubt cousin & aunt will want.  Do not want to show up and refuse to eat their cake, but I have to protect my little one.  Suggestions on how to handle??