This varies from person to person and also depends on your end goals: weight loss, mental or athletic performance or disease management/cure. That said, here are some suggested ranges depending on each goal:
Weight loss: > 0.5 mmol/L
Athletic performance: > 0.5 mmol/L
Mental performance: 1.5 - 3 mmol/L
Therapeutic purposes: 3 - 6 mmol/L
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