Answer
The muscles involved in the action of "sucking in the gut" are the following:
External abdominal obliques
Internal abdominal obliques
Transverse abdominis
Rectus abdominis
Work Step by Step
These muscles compress the abdominal organs during forceful expiration, in vomiting, in urination, in defecation and in childbirth.
The phrase "Suck in your stomach" is sometimes used , But this is anatomically incorrect.
