Hunger grumps, otherwise known as being "hangry", is a common sign that you need to raid your cupboards for some sustenance right now.
When you suddenly start thinking about eating your way through a whole pack of cookies.
One of the telltale signs that you are hungry is when your belly actively cries out, saying "feed me, feed me" in a low rumbly voice.
You need to refill your fuel supplies when every action takes twice as long to carry out.
An unexpected urge to nap at a time when you're usually awake means your energy is low and needs something to refuel.
You should take a food break when you are getting easily distracted and not able to focus on the task at hand.
Not having the energy to carry out usual daily tasks.
Feeling shaky or weak is a very easy sign to tell that your blood sugar levels are low.
If it's been a while since your previous meal, you are probably hungry even if you don't necessarily feel other symptoms. A regular schedule of mealtimes each day should solve this.
When you start thinking about food, it's probably because you want to eat that food.