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Invited review: Aging and energy balance
Margaret-Mary G Wilson1, John E Morley
1Division of Geriatric Medicine, St. Louis Univ. School of Medicine, 1402 S. Grand Blvd., M238, St. Louis, Missouri 63104, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 13, 2003
Summary
Older adults often experience physiological anorexia and sarcopenia, leading to unintentional weight loss. These age-related changes in appetite, metabolism, and energy expenditure increase the risk of pathological weight loss, especially during illness.
Area of Science:
- Gerontology
- Human Physiology
- Nutritional Science
Background:
- Older adults (over 70) frequently experience weight loss.
- This is attributed to physiological anorexia of aging, sarcopenia (loss of lean mass), and reduced fat mass.
Purpose of the Study:
- To investigate the physiological mechanisms underlying weight loss in aging humans.
- To identify factors contributing to reduced energy intake and expenditure in older adults.
Main Methods:
- Review of physiological changes associated with aging, including sensory perception, gastric function, hormonal regulation, and metabolic processes.
- Analysis of factors influencing energy expenditure, such as resting metabolic rate, muscle activity, and thermogenesis.
Main Results:
- Aging alters taste and smell, reduces stomach fundus relaxation, and increases satiating hormones (cholecystokinin), leading to early satiety.
- Declining testosterone in men correlates with increased leptin and lean mass loss.
- Reduced resting metabolic rate is primarily linked to decreased lean body mass and diminished Na+-K+-ATPase activity.
- Physical activity and meal-induced thermogenesis decrease with age, potentially due to delayed gastric emptying.
Conclusions:
- Physiological anorexia and sarcopenia are key drivers of weight loss in aging.
- These age-related metabolic and functional changes predispose older individuals to pathological weight loss, particularly when disease is present.