My husband is gluten free and has to travel and he doesn't have a problem when he stays in chain hotels as long as he (a) mentions it when booking (b) reminds them at check-in.
People are used to making arrangements for special diets these days e.g. vegetarian, vegan, gluten free, lactose free, nut free, halal and kosher. There's nothing wrong in saying you need low carb food because you're on a diet or telling the course providers that you have a carbohydrate intolerance.
Why do you, person with a **** relationship with food, have to be the one to cook for the team ? Why couldn't you get excused from that to cook for yourself or have them do you simple low carb ?
I'm sorry to hear about your mother but maybe now she will be more supportive and your dad will have to eat low carb too.