Eating meaningfully fewer calories long-term, while keeping complete nutrition, reliably improves blood pressure, cholesterol, blood-sugar handling, body fat, and inflammation in humans. Whether it slows aging or extends life stays unsettled. The trade-offs — lost muscle and bone, a slower calorie-burning rate, lower sex hormones, and constant hunger — matter most for already-lean, active people. (Full Review)
| Marker | Target | Why |
|---|---|---|
| Body composition (lean & fat mass) | Preserve lean; reduce excess fat | Confirms loss is fat, not muscle |
| Bone mineral density (T-score) | Above −1.0 | Detects bone loss early |
| Fasting glucose | 70–90 mg/dL | Tracks glucose regulation |
| Fasting insulin | 2–6 µIU/mL | Sensitive early marker of insulin sensitivity |
| HbA1c | < 5.4% | Average blood sugar over ~3 months |
| Lipid panel (LDL, HDL, triglycerides) | LDL < 100; triglycerides < 80; HDL > 50 mg/dL | Cardiovascular risk |
| hs-CRP | < 1.0 mg/L | Tracks systemic inflammation |
| IGF-1 | Age-appropriate low-normal | Reflects growth-signaling down-regulation |
| Testosterone (men) / menstrual regularity (women) | Mid-normal for age / regular cycles | Detects excessive hormonal suppression |
| Thyroid panel (TSH, free T3) | Free T3 mid-normal | Detects metabolic down-regulation |
| Albumin & complete blood count | Albumin 4.0–5.0 g/dL; normal counts | Screens for undernutrition |
Cadence: Baseline, 4–8 weeks, 3 months, 6 months, then every 6–12 months; earlier for anyone on glucose- or blood-pressure-lowering medication