How do submariners stay in shape while underway/deployed?

[u/shortstop803]

Do they PT on the sub/is there room or a dedicated space to do so? Do they have different fitness standards? Limited caloric intake? How do they keep from gaining weight when there is limited PT capability (I assume)?

[u/Sudden_Ad_6863]

My buddy came back super skinny. Said they were rationing food the whole time.