When a player is nourished enough to receive the 'Healing' or 'Healthy' status, and the player has blood taken from them (with a blood bag); the Healing/Healthy status is lost, and does not return until the status is lost and regained.
The player will still regenerate blood at the rate of their (now invisible) status), but there is no visual indicator as there should be.
I do not think this affects damage-based blood loss, but I can't be 100% certain.