Anonymous wrote:sallow complexion vs. rosy complexion
thin, dry hair vs. shiny thicker hair
low muscle tone vs. tighter muscles.
dark circles that are not hereditary
Poor posture while standing and sitting. someone who has a strong core will sit up straight and walk with shoulders back and lots of confidence. Someone with a weak core will shuffle when they walk, hunched over a bit.
This is really silly. My DD has low muscle tone, and believe me, she is naturally thin. Dry hair has nothing to do with whether you are naturally thin. I had dry hair when I was overweight. Ditto complexion and dark circles, which are often caused by allergies.
I don't think there is any way to tell. You can assess eating habits, but even there, people who eat and espouse "healthy" foods are often the most disordered and naturally thin people often eat a lot of crap.