I appreciate the this observation is what you observed, based on your personal experience practicing radiology. And it is an interesting observation. Are you aware of any studies that can substantiate it, or better yet point to causation? Or address long term heath outcomes for each diet type?
It’s definitely possible, for example, that serious carnivores also tend to focus on resistance training, while vegans tend to exercise less or focus on lower weight aerobic exercise like running. That alone could explain the differences in muscle mass that you observed between the two groups. Teasing out a confounder like that requires a clinical trial of some sort.
On the other hand, you saw images of bodies and physical effects of diet (and exercise) but what about long term health outcomes? How do those compare across all three groups? What if the bodies look similar, but one diet is more pro-inflammatory or carcinogenic? Those effects would not be so visible on body scans.
It may be misleading to generalize a limited set of nonetheless interesting observations that can’t account for confounders or unintentional biases.
I would argue that, while point-in-time observations can be a starting point, only well-powered, well-designed clinical studies can reliably answer these questions.
