I find this discussion to be fascinating, as you follow the twists and turns from the original comments. I have at least two siblings who are vegetarians or vegans, yet have moderately controlled sweet-tooths. Myself, due to kidney issues, eat a low potassium/low phosphorus/low sodium diet, with almost no dairy. Plus low purine due to gout [no shellfish, mushrooms, pork]. Very little red meat, lots of chicken and fish; some day I will wake up clucking! Yes, as @ayeshasharma said, poor eating and depression are linked, ask me how I know!
Ginger