All of the things mentioned in other comments. However my burnout also lead to chronic fatigue syndrome, which (at least for some people) seems to be caused by

All of the things mentioned in other comments. However my burnout also lead to chronic fatigue syndrome, which (at least for some people) seems to be caused by extreme burnout. Severe depression/anxiety, inability to digest much food, severe fatigue (not able to walk very far, if at all), vertigo/POTS, disrupted sleep cycle, feeling very cold, etc. Some people get chronic pain as well.