A natural state, I'm sought by all.
Go without me, and you shall fall.
You do me when you spend,
and use me when you eat to no end.
What am I?
I think it is
Balance
Explanation as follows
A natural state, I'm sought by all.
In nature, everything is balanced by default. And balance is sought by all
Go without me, and you shall fall.
Without balance, we will definitely fall.
You do me when you spend,
When you spend, what left off will be the balance
and use me when you eat to no end.
I am not sure about this one. May be it is 'if you eat everything there won't be anything balance'
I believe the answer is
Energy
Because:
A natural state, I'm sought by all
Whether it be just to live or to power our vehicles, lights etc.It all qualifies as energy. Wars have been waged to obtain valuable resources that ultimately gets used for energy. I am referring to oil and fossil fuels here.So in a natural state it could either be the energy we as humans have or the natural energy that resides within our earth/universe
Go without me, and you shall fall.
This speaks for itself, but without any energy you would surely fall.See the end of many marathons or exertion competitions. Many people collapse
You do me when you spend,
This can be referred to the act of actually buying things or it could be that you expend or spend energy to do pretty much anything.
and use me when you eat to no end.
When we eat our body uses energy to process all the food and generally when we eat to no end, we will either become fat, which means your body uses more energy to sustain it anyway, or you become sick, which largely drains our energy.
Upon using google I found that the answer given by @AeJey is the widely chosen one. Though I feel this one fits the riddle better. Even if my explanation is not correctly executed, I feel the answer fits better.