A note of caution, somewhat unrelated to your marriage but not really.
Size 00 combined with worry about a 300 calorie meal is a big red flag for an eating disorder or at least the slippery slope toward one. 1200 calories a day is the recommended healthy *minimum*.
If she is not getting enough nutrition on a regular basis, her brain isn't going to be functioning up to standard, and all your efforts will be faced with a substantial drag factor. Not to mention the possibly serious threat to her general health.
Be aware.
"Show me a completely smooth operation and I'll show you someone who's covering mistakes. Real boats rock." -- Frank Herbert
