Ask food to a flight attendant

I'm heading to Ushuaia, Argentina now. I bought a cheap(?) tickets,
it means I have to transfer many flights, and I also have to wait much time 
for the next flights in many airports.
I was very sad, when I saw people who threw out food after meals on the planes.

Many my friends said, "Kim, if you are really hungry, go to a restaurant, and ask food.

If they can't sell food, they have to throw away. It's better to give you."
But I never once tried on the road for more than 2 years.
Because I was embarrassed and not very brave enough to ask.
But I did it on the airplanes. I'd rather eat leftovers than wasting food.
Now, I really don't think it's embarrassing. And no problem, I can be embarrassed for a moment,
I don't care if people think I'm a beggar or not. Food was still eatable and tasty. 
And nobody wanted except me. 
At least, I did something good for myself and for the world. That's it.