I’m low carb these days and just avoid all bread/pastry items, and only eat a moderate amount of any carb on the main dish. No snacks between meals, especially crisps, and now tend to eat little of the 2nd meal (not at all if it’s breakfast on an overnight). Generally avoid carb-laden lounge options too. Overall I resist the urge to eat everything offered to me (my former habit) and I find sipping sparkling water a handy way to resist the urge to snack on carbs.

Carb avoidance can can be more of a challenge on short haul, especially on afternoon tea departures, though not eating at all on those flights is easier.