To whit: I run a men's lifestyle Q&A site. I have a total of 25 categories in which questions are submitted. Currently, however, these "categories" are in fact sub-categories, such that Bodybuilding, Cardio, Nutrition, Health and Sports for example, all belong to the "Health & Body" meta category, of which there are 5 in total.
Is this the best structure for the site, or would it be better for SEO to upgrade the sub-categories (since there are - and probably always will be - only 25...) into full-blown categories?
Thanks very much in advance for any light you're able to shed on this.