Longevity · Body composition
Body composition and ageing
How muscle, fat and bone change with age, why muscle strength matters, what sarcopenia is, and simple ways to track body composition.
Written by LON6EVITY Editorial Team · Last updated
What changes with age
With age, muscle mass and strength tend to decline and fat tends to shift toward the abdomen, even when body weight stays the same.
Sarcopenia
The European Working Group on Sarcopenia in Older People (2019) defines sarcopenia as a progressive loss of muscle strength and mass, with low muscle strength as the main criterion, and links it to falls, fractures and loss of independence.
Weight is not the whole picture
WHO uses body mass index for population statistics, but BMI does not separate muscle from fat. Waist circumference, grip strength and, where appropriate, DXA-based measures give a fuller picture.
Factors that can affect the result
- Resistance exercise
- Protein intake
- Physical activity
- Hormonal changes
- Chronic illness
Questions people commonly ask
- How can I track muscle health at home?
- Simple measures like grip strength or chair-rise tests are used in research and clinics; ask a clinician for a formal assessment.
- Is BMI useless?
- No, but it cannot distinguish muscle from fat, so it is best used with waist size and other measures.
Related tests
Related topics
Build your longevity profile
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- Sarcopenia: revised European consensus on definition and diagnosis. Cruz-Jentoft AJ et al., Age and Ageing, 2019.
- Obesity and overweight — fact sheet. World Health Organization.