In Western societies, individuals typically undergo weight gain until around the age of 50-60, followed by a phase of weight steadiness, ultimately leading to a propensity for weight loss.
Throughout gestation, there is a general escalation in body fat concentration until birth, followed by a subsequent reduction in water content from birth to adulthood. Premature infants may undergo additional water loss associated with age-related changes in fat content.
The advancing comprehension of age-related alterations in body composition underscores its potential as a factor that can be modified in the pursuit of optimal health, functionality, and longevity.
Despite a reduction in water content, there is an elevation in nitrogen content, signifying a higher concentration of protein in adult tissues compared to newborns or fetuses.
Changes in extracellular fluid volume, shifting from a greater to a lesser extent with growth, are observable in the diminishing sodium concentration in body tissues linked to aging, along with an upsurge in potassium concentrations.
Minerals such as phosphorus, magnesium, and calcium, predominantly present in bones, witness a significant increase from birth to adulthood during the body's mineralization process.
While proportions of body water in the central nervous system, skin, and subcutaneous tissue decrease, other organs, particularly muscles, undergo an augmentation. These patterns persist throughout the aging journey.
In Western adults, a gradual decline in lean body mass and an accrual of fat transpire from early adulthood onward, coupled with a reduction in muscle mass and bone mineral density.
Not only do older individuals harbor more body fat than their younger counterparts, but the distribution of fat also diverges. Older individuals exhibit a higher percentage of intra-hepatic, intramuscular, and intra-abdominal fat, changes associated with insulin resistance in both young and older adults.
The decrease in lean body mass is more conspicuous in men than in women until after menopause when it accelerates. This shift is primarily ascribed to the loss of cellular versus extracellular mass, resulting in average losses of 22.5% in potassium and 17.5% in nitrogen from ages 25 to 75, for both genders.
As a result, the elderly confront debilitation and a substantial decrease in tissue amino acid and energy reserves.
Body Composition Changes
