These days, I make a point to force myself to decline food unless I feel genuinely hungry whilst I’m travelling. For no other reason than (not wanting to be too graphic) my natural digestive rhythms simply do not run normally when I’m travelling – particularly air travelling.
It used to be so tempting to just fill my face with something at every juncture of my journey - breakfast in the morning, food and drinks at the lounge, service on board (typically another two meals including deserts, alcohol etc) an evening meal on arrival etc etc - which is far, far more than I would ordinarily eat and drink in a day (not to mention far less activity). Combined with the effects of flying on your physiology, body clock, digestive system it was all too common for me to feel really nasty after flying long haul. So now I ensure that I exercise some restraint wherever I can to try and mitigate all that. I’m really only designed to eat a maximum of 2 or 3 moderately sized meals anyway (rarely eat a full breakfast, lunch and dinner at home) so I stick to this when travelling.
Even on holiday I’ll ensure I stick to a few odd days of “intermittent fasting” where I restrict my intake to <1000 calories. Not that hard to do I find as there is always something very light/veggie/salady you can eat and generally I find occasional fasting days – even in my daily life - helps keep my weight under control but still enjoy all the foods I love on non-fasting days.