Are you actually hungry?
"I'm soooo hungry!" "I'm starving!"
But stop and think for a moment. Are you truly and actually hungry?
Here's one way to tell:
Pick a food you really don't like, but something healthy. Like spinach. Or broccoli. Or turnips. It'll be different for everyone.
Now pretend that's the only food available.
Still want some?
If it sounds appetizing and you could see yourself eating it, you're probably hungry.
If not, you're not hungry. You're likely upset, bored, or otherwise distracted.
In this case, try getting up and doing some sort of physical exercise. You'll probably forget about food altogether and start doing something productive instead!