Effect of aging on body fat

Area of Science:

• Gerontology
• Human Physiology
• Body Composition Analysis

Background:

• Aging is often associated with changes in body composition, particularly an increase in body fat.
• Previous research has suggested a significant rise in body fat percentage with advancing age.
• However, confounding factors like changes in body mass index may have influenced earlier findings.

Purpose of the Study:

• To investigate the relationship between aging and body fat percentage.
• To determine if body fat percentage increases significantly with age after a certain point.
• To differentiate between age-related fat increase and weight gain in older populations.

Main Methods:

• A cross-sectional study comparing body fat percentage across different age groups and genders.
• Participants (n=697) were recruited from community health fairs, a medical school, and a veterans' nursing home.
• Body fat percentage was measured using bioelectrical impedance analysis (RJL Spectrum Bodycomp II).

Main Results:

• Body fat percentage showed a slight increase between ages 20-39 and 40-84.
• No significant differences in body fat percentage were found among age groups 40-84 when age-matched for body mass index.
• Individuals over 85 years had significantly lower body fat percentage; nursing home residents had lower body fat than ambulatory individuals.

Conclusions:

• Body fat percentage does not appear to increase significantly after age 40.
• Weight gain, rather than a true age-related increase, is the main factor contributing to higher body fat in older adults.
• Studies reporting marked increases in body fat with age may not have adequately controlled for body mass index variations.