Whenever I'm flying long distances, I always buy a meal deal at the airport and take various snacks with me, such as Soreen mini snacks, bags of chopped fruit/veg, hummus and carrot sticks, pop chips etc. because I find that having something to nibble on makes the journey more interesting!!
Earlier this year I flew to Vietnam with Malaysian Airlines and was glad I'd stocked up on snacks, because the flight was around noon and they fed us on-board at 1pm, then served an inedible biscuit at 5pm and dinner was served at 11pm. So it was 10 hours between the meals!! I was so glad, I'd bought the meal deal, as I was ravenous about 6pm, so I ate it then.
On every other long haul flight I've been on, they've provided free snacks in the galley, that you can help yourself to, but Malaysian Airlines didn't provide anything.
Also, the dinner choices were exactly the same as the lunch choices, neither were appealing, one was spicy shrimp, can't remember what the other was, but I know I had it for both lunch and dinner!
Others in the group hadn't taken any food on-board and when they were hungry, they asked the staff for a snack and were told there weren't any.
A few people flew business class and said the food was exactly the same as economy and they didn't have any snacks either.
So my advice is, if you're flying with them, take food with you!