a negative impact of refined foods
Talking about diet is dangerous because there are many opinions and few verifiable facts. Therefore, it makes sense to find opinions that seem to make sense and resonate with you and adopt those until one of those scarce and elusive facts proves your opinion to be false.
I have been moving into the camp of those who believe that the healthiest foods are as near to unaltered as possible, i.e. unrefined.
One explanation that I have heard regarding obesity in America is that refined foods are the cause. When plant matter is refined, material is removed. With the removal of that matter, often minerals and vitamins are removed as well. So, even though we may be eating vegetable-based foods, it often does not resemble the vegetable it is based from (corn chips, cereal grains, etc.).
The explanation states that our bodies begin to lack certain nutrients that it is accustomed to receiving from that food and so becomes starved for that particular nutrient. Thus we continue to eat, hoping to acquire sufficient amounts of the missing nutrient. We eat more because our body needs absent nutrients, so no matter how much we eat, we will not acquire those nutrients.
Is it true? Has it been verified? No. But, it has not been proven false either. Until then, I will believe it because it makes sense to me.