How to ruin someone's day

Conversation about my upcoming race tomorrow:

Him (my manager and experienced marathon runner): Don’t have pasta tonight

Me: What?

Him: Just don’t have pasta tonight! I know people that the day before a race had an overload of pasta and were feeling very bloated and uncomfortable during their run. No pasta party for you!

Me: Don’t tell me that! I was really looking forward to having spaghetti meatballs tonight (JJ's making them special).

Him: Remember what I've told you. At least don’t have a second serving!

Me: I’ll try (Booooo) L