From what I learned, fiber is the non-nutritional part of foods that end taking part of the bulk of stools.
With some seen emphasis on the importance of fiber intake; does it mean that poorly nutritional foods are also good to have ?
How does it work ?

 

Fiber does not necessarily mean poor nutritional foods.  For example-- eating lots of vegetables (particularly things like Broccoli) will give you plenty of fiber.  Certain fruits and beans provide a similar benefit in terms of fiber.  All you need to do is eat a little less meat and fewer highly processed foods.

The primarly important thing in your diet are calories, these things makes you survive xD then protein and vitamines, fibers primarly prevent constipation and help lower blood cholesterol and glucose levels