Originally Posted by tical

Protein is the primary building block of our bodies. If you were building a brick house, they'd be the bricks.

Our cells are constantly turning over and if you don't have enough protein you'll enter a catabolic state where lean mass (muscle, organs, bones) start to break down in order to support this metabolic process. Your body basically begins eating away at itself.

Add to this insufficient calories via carbohydrates and fats (i.e., only eating vegetables) and you'll feel miserable as hell. You're essentially fasting.

In turn your metabolism will slow down tremendously making you extremely weak, tired, and lethargic. It does this as a survival mechanism. It will be hard to think clearly, cognition will suck, etc. The neurological impacts of an impaired metabolism are tremendous and can definitely lead to an altered / gloomy (and sometimes dreamlike) state of mind.

Glad to hear you're better.