Looking at the "muscular scale" on the athletic wiki page, would something like this be a proper structure:

Muscular scale

Chubby scale

Slim scale

Any thoughts, additions, other suggestions?

There is issue at least where anorexia is a tag for just a phenomenom, whereas anorexic has been aliased to it, thought it would be needed for anorexic_female, anorexic_furry etc.

I don't think a character can be skinny and muscular at the same time, or skinny and chubby either, but not sure about muscular and chubby (e.g. that musclegut concept).

Concerning topic #19547 this would be yet another template.

There is some prior discussion on body types like this on topic 26344

There is also tag_group:figures wiki page.

Those are actually some neat scales. It gives a clear overview of what tags are used to describe body types. It can aslo redirect users much faster through the various wikis in case they need a better explanation.

urielfrys said:
There is issue at least where anorexia is a tag for just a phenomenom, whereas anorexic has been aliased to it, thought it would be needed for anorexic_female, anorexic_furry etc.

I’m not so sure on this tag either
I think anorexia can still fit within the scale for extremely skinny body types. It doesn’t necessarily have to define the irl medical condition.

urielfrys said:
I don't think a character can be skinny and muscular at the same time, or skinny and chubby either, but not sure about muscular and chubby (e.g. that musclegut concept).

The first two comparisons don’t work, but the last one makes sense. musclegut is a tag that describes a character who has a hefty/bulky body type, so someone with muscular body parts (such as biceps and quads) as well as a noticeable belly instead of abs.
Musclegut works well in the scales.

zenith-pendragon said:
I think anorexia can still fit within the scale for extremely skinny body types. It doesn’t necessarily have to define the irl medical condition.

This might be going off on a tangent from the OP, but anorexia is a terrible tag name for describing anything but the eating disorder, there are good reasons why after fourteen years from the first time it was ever added to a post there are only 107 posts. It's not an intuitive tag to add for a very skinny character, it's inaccurate, and it could be taken pejoratively when added to characters that are just naturally very skinny or are drawn in a stylized way that makes them cartoonishly thin.

As for skinny, the problem is that it's poorly defined (the wiki page is badly written and unhelpful), and tagging is all over the place,

The problem is that it's used for "visibly skinny" characters with very narrow bodies, thin limbs, etc. as well as relatively "average" bodied characters that aren't particularly curvy, fat, or muscular. I don't know what should be done to fix skinny, but I think there should be an extremely_skinny tag ("extremely" might be overselling it, but I'm not sure what adjective could get us out of this chubby/slightly_chubby situation) to apply to characters like the ones below.

I've earlier had problems with the athletic-slim-skinny scale, before I now gathered this whole structure. Not being familiar with the latter two, I thought all non-overweight would be considered athletic, unless going towards the muscular side.

I think extremely_skinny would be a good tag for characters that I would currently think of tagging as anorexia: When the body is thin beyond what would appear in any ways healthy. The difference between athletic and slim would be that athletic seems like they participate a lot of physical activity and are in great form, without yet having visible muscles (athletic: soft_abs, muscular: abs) and skinny (in comparison to slim) would have more straight lines / less curvature. Partially lanky. Perhaps with the appearance of being physically weak.

If we were going to rename tags to disambiguate, I think underweight would be a better match. In common usage, people use skinny to refer to people of a normal healthy weight, or even slightly above, so long as they're not overweight. Aliasing slim(and variations like slim_male) to skinny, and using the underweight tag for truly underweight characters would be the most clear way to distinguish skinny vs slim

I think a character could be skinny and muscular, if not just athletic
post #3105190
this depicts a character with wiry definition, but noticeably small arms and a very gaunt ribcage. I might change the label above athletic to say "slightly muscular"(counterpart to slightly_chubby I guess), and change the stuff to the left of athletic to say "not muscular". (also, maybe alias slightly_muscular to athletic, or the other way around if the muscularity is the defining point). This would change muscular to match overweight, so that it's just a scale of size

aliasing athletic to slightly_muscular would help in the case of characters that are slightly_muscular, but still overweight, yet not muscular enough to be musclegut

solo overweight muscular -musclegut ~female ~intersex breasts
Musclegut is a somewhat male slanted(dad bod slanted) tag. The above search returns a reasonable number of characters who are overweight or chubby, yet not all as muscular as musclegut characters
post #3675849
This Toriel is certainly squishy, but she has rather defined(if not particularly bulky) triceps

This question is discussed also in post #30445: Slightly chubby sexes BUR

maplebytes said:
This might be going off on a tangent from the OP, but anorexia is a terrible tag name for describing anything but the eating disorder, there are good reasons why after fourteen years from the first time it was ever added to a post there are only 107 posts. It's not an intuitive tag to add for a very skinny character, it's inaccurate, and it could be taken pejoratively when added to characters that are just naturally very skinny or are drawn in a stylized way that makes them cartoonishly thin.

As for skinny, the problem is that it's poorly defined (the wiki page is badly written and unhelpful), and tagging is all over the place,

The problem is that it's used for "visibly skinny" characters with very narrow bodies, thin limbs, etc. as well as relatively "average" bodied characters that aren't particularly curvy, fat, or muscular. I don't know what should be done to fix skinny, but I think there should be an extremely_skinny tag ("extremely" might be overselling it, but I'm not sure what adjective could get us out of this chubby/slightly_chubby situation) to apply to characters like the ones below.

emaciated is a tag that exists for extremely skinny characters, almost 350 posts

urielfrys said:
This question is discussed also in post #30445: Slightly chubby sexes BUR

you mean topic #30445, post # is for like /posts posts.

I thought emaciated was for any extremely skinny character and anorexia was for actual depictions of the eating disorder