Your body monitors the nutrients it needs (our bodies know more than science...), and if a nutrient is low, our body tells us to eat. That's it - because for thousands of years, that's all we had to do was eat whole foods (or only slightly processed grains for bread, etc.). But now we have food that is devoid of nutrients due to processing - but our bodies don't know this - food is supposed to contain lots of nutrients.

Nutritional value food became understood when researchs were carried out than the body telling us, although it did but the meaning were limited in knowledge.

Explanation:

In as much as most food are allowed into the body, some of them lack nutritional values to grow the body. When proper research weren't yet carried out, people ate basically anything good so long it was accepted by their body. The body might have reacted or not. And for some that it didn't react we later discovered that they didn't really have values to add to the body but were just taken to push aside hunger. Nutritional value food became understood when researchs were carried out than the body telling us, although it did but the meaning were limited in knowledge.