The ketogenic diet cuts carbohydrates low enough to burn fat for fuel. Its most dependable benefits are lower blood sugar and insulin, improved blood fats, and short-term fat loss, strongest in those with blood-sugar or weight problems. Longevity interest comes from its overlap with fasting, but human lifespan data are lacking. Cholesterol can rise, and long-term safety stays unsettled. (Full Review)
| Marker | Target | Why |
|---|---|---|
| β-Hydroxybutyrate (blood) | 0.5–3.0 mmol/L | Confirms nutritional ketosis |
| Fasting glucose | 70–90 mg/dL | Tracks glycemic response |
| HbA1c | < 5.4% | Average blood sugar over ~3 months |
| Fasting insulin | 2–6 µIU/mL | Core marker of insulin sensitivity |
| HOMA-IR | < 1.5 | Calculated insulin-resistance index |
| Triglycerides | < 80 mg/dL | Drops reliably on low-carb; heart-risk marker |
| HDL cholesterol | > 50 mg/dL (women), > 45 (men) | Tends to rise on the diet |
| LDL cholesterol | Context-dependent | Flags the diet's key cardiovascular concern |
| ApoB | < 90 mg/dL (lower if higher risk) | Best single marker of atherogenic particle burden |
| hs-CRP | < 1.0 mg/L | General marker of inflammation |
| Sodium, potassium, magnesium | Mid-normal range | Depleted by the diet's diuresis |
| Uric acid | < 5.5 mg/dL | Can rise early; gout/stone risk |
| Free T3 | Mid-to-upper normal | Can fall with heavy carb restriction |
| eGFR & creatinine | eGFR > 90 mL/min/1.73m² | Kidney safety, especially with stone risk |
| ALT / AST (liver enzymes) | < 25 U/L | Tracks fatty-liver improvement |
| Coronary artery calcium (CAC) | 0 (Agatston score) | Contextualizes a lipid rise |
Cadence: Electrolytes and symptoms at 1–2 weeks; full lipid panel with ApoB and metabolic markers at 6–12 weeks; then every 3–6 months while on the diet.