mesomorphs

/M EH0 S AH0 M AO1 R F S/
noun
  1. 1

    A person with pronounced muscular development and low body fat.

  2. 2

    : Theoretical body type in which a person naturally has lower body fat and greater ability to achieve muscular development than average.

Source: https://en.wiktionary.org/wiki/mesomorph, https://en.wiktionary.org/wiki/mesomorphs