Introduction -- Part I: Connecting the dots. What we're doing isn't working: mental health today -- What causes mental illness and why does it matter? -- Searching for a common pathway -- Could it all be related? -- Part II: Brain energy. Mental disorders are metabolic disorders -- Mental states and mental disorders -- Magnificent mitochondria -- A brain energy imbalance -- Part III: Causes and solutions. What's causing the problem and what can we do? -- Contributing cause: genetics and epigenetics -- Contributing cause: chemical imbalances, neurotransmitters, and medications -- Contributing cause: hormones and metabolic regulations -- Contributing cause: inflammation -- Contributing cause: sleep, light, and circadian rhythms -- Contributing cause: food, fasting, and your gut -- Contributing cause: drugs and alcohol -- Contributing cause: physical activity -- Contributing cause: love, adversity, and purpose in life -- Why do current treatments work? -- Putting it all together: developing your metabolic treatment plan -- A new day for mental and metabolic health.