Body composition and mortality risk in later life

Area of Science:

• Gerontology
• Body Composition Analysis
• Mortality Studies

Background:

• Body mass index (BMI) is a common but limited measure for defining overweight and obesity.
• While BMI-mortality links are known for middle age, they are less clear for older populations.
• Further research into body composition and mortality in older adults is essential.

Purpose of the Study:

• To examine the associations between various body composition aspects and mortality risk in individuals aged 65 and older.
• To differentiate the impact of lean mass, total fat mass, and fat distribution on longevity in the elderly.

Main Methods:

• Utilized dual-energy X-ray (DXA) absorptiometry to measure body composition in 921 participants (≥65 years).
• Measured total, abdominal, and gynoid fat masses, along with lean body mass at baseline.
• Followed the cohort for a mean of 9.2 years to record mortality events.

Main Results:

• Lean mass demonstrated a significant negative association with mortality in both men and women (P < 0.001).
• Total fat mass exhibited a U-shaped association with mortality in men (P < 0.01) and a negative association in women (P < 0.01).
• An increased abdominal-to-gynoid fat mass ratio elevated mortality risk in women (P = 0.04), but not in men (P = 0.91).

Conclusions:

• Lean body mass is a strong predictor of survival in older individuals.
• Increased fat mass appears protective for older women, whereas extremes of fat mass (very low or very high) elevate mortality risk in older men.
• Further investigation is required to elucidate the underlying biological mechanisms driving these body composition-mortality relationships.