Protein & Longevity: How the Science Has Shifted (2017 → 2026)
Figure 1. Based on a survey of over 1500 people of 65 and over in the UK (source: @SilverM00NSHOTS) Figure 2. Rockwood frailty index [61] For years, longevity discussions emphasized restricting protein to avoid overstimulating IGF‑1 and the mTOR pathway. Early frameworks—such as the 2017 Mitochondrial Metabolic Therapy diet—recommended 45–55 g/day to minimize nitrogen load, reduce IGF‑1, and limit mTOR activation. These concerns were grounded in real physiology: excess protein can increase nitrogen waste, elevate IGF‑1, and activate growth pathways linked to cancer risk. [17,47] But as the population ages and long‑term data accumulate, the scientific lens has widened. By 2026, the consensus has shifted: for older adults, the more urgent and measurable threat is muscle loss—not moderate protein intake. The 2026 Update: A Higher Baseline for Healthy Aging Recent clinical guidelines now recommend 1.0–1.2 g/kg of body weight for most healthy older adults. For those ...