I understand the image, but I have still never heard it used that way.
Some call my 6 year old nephew "chunky" meaning he is stocky.
www.dictionary.com gives two definitions.
chunk·y ( P ) Pronunciation Key (chngk)
adj. chunk·i·er, chunk·i·est
1. Short and thick; stocky.
2. Containing small thick pieces: chunky peanut butter; chunky soup.
You might be correct that your usage is a form of definition 2.
But I have never heard it used this way for a persons physical appearance. I have always understood that a "chunky" person was "short and thick".