Sarcopenia — What It Is, Why It Accelerates
Muscle loss isn't just losing 'tone'
Sarcopenia is the age-related loss of muscle mass + strength. Lean mass starts declining ~3–8% per decade from 30, accelerating to 8–15% per decade after 60. Strength loss runs even faster than mass loss because neural drive declines too. By 80, untrained adults have lost roughly 30–40% of their muscle.
Anabolic resistance — the older-adult catch
Older adults need MORE protein per meal to trigger the same muscle protein synthesis as younger adults. Younger adults max out muscle synthesis at ~20 g protein per meal; older adults need 30–40 g. This 'anabolic resistance' means the standard protein recommendations (0.8 g/kg/day) are inadequate for adults over 50.
Muscle is metabolic real estate
Beyond movement, muscle stores ~80% of the body's glucose disposal capacity. Less muscle = worse glucose handling = higher insulin resistance = downstream metabolic disease. Sarcopenia and metabolic dysfunction reinforce each other — fixing one fixes some of the other.
Type II fibers go first — power before strength
Fast-twitch (Type II) fibers atrophy 2–3× faster than slow-twitch (Type I) with age. That's why power declines before strength: explosive recovery — the kind that prevents a stumble becoming a fall — depends on Type II. Heavy lifting at moderate-to-fast tempo, jumps, and plyometrics preserve Type II better than slow-tempo bodybuilding work.
Match life-stage to protein need
Connect each adult-life stage to the daily protein target for muscle preservation.
This step is interactive — open the Thier app to try it.
Key Takeaway
Sarcopenia starts in your 30s and accelerates after 60. Anabolic resistance means older adults need MORE protein, not less. Muscle isn't just about strength — it's metabolic real estate that protects against insulin resistance and frailty. Both lifting + protein matter equally, and Type II preservation needs explosive intent — heavy + fast, not just heavy.