Natural peanut butter contains healthy fats whereas non-natural will contain artificial ingredients to enhance the taste. Non-natural peanut butter is often drained of the good fats and sugar % is much higher for example.
Protein and fibre is a good source of nutritions in natural peanut butter also
used right it can aid weight loss as you feel fuller from these nutritions. A FB friend of mine has apples with natural peanut butter, apparently it is nicer than it sounds
Hope that helps ... I'm actually starting to learn more about healthy fats, complex carbs, etc only recently whereas previously peanut butter was a big NO!