Well paleo advises to stay away from starchy foods and vegetables like corn, potato and some others...
If you look somewhat at the progression there was Atkins that was meat/saturated fat focussed and even tended to avoid vegetables and fruits...
Then paleo is also generally meat-focussed but only avoids certain starchy vegetables along with grains/dairy and their products and is also recommending most nuts(apart from peanuts), fruits, healthy oils, etc...
Of course these are all essentially low carb diets since that tend to turn the traditional "food pyramid" upside down and recommend staying away from most grains and grain-based processed products...
You can read some books like "grain brain" and "wheat belly" others like "White poison"
" to get a better idea of why grains/sugar are generally recommended to be an "avoid" these days by these sort of diets...
In the US they fundamentally turned their entire food chain into corn/wheat/soy dependent (even animals are fed corn/soy products) and have a look at the massive obesity and health problems they deal with...
I kind of find it satisfying to walk into a supermarket and probably 98% or the items on sale from the shelf after shelf of breads and processed foods, I have absolutely no interest in buying and even walking through a food court there is almost nothing I would buy to eat apart fro...
Of course if diets like the paleo diet become widespread, the fastfood industry as well as supermarkets might find they need a significantly different product mix to continue thriving and so you will obviously get a lot of trolls deriding such food choices as "diet fads"...
