Total energy expenditure in the elderly.

Area of Science:

• Gerontology
• Human Physiology
• Nutritional Science

Background:

• Aging is associated with increased chronic diseases and disabilities, impacting daily activities.
• Understanding energy expenditure is crucial for managing health in older adults, both healthy and diseased.

Purpose of the Study:

• To analyze total energy expenditure (TEE) and its components (basal metabolic rate, physical activity, thermogenesis) in aging populations.
• To investigate how chronic diseases affect TEE in elderly individuals.

Main Methods:

• Analysis of 568 doubly labeled water measurements in healthy subjects, including 184 over 65 years.
• Inclusion of 136 measurements from elderly patients with various diseases using doubly labeled water and bicarbonate-urea methods.

Main Results:

• A decrease in TEE with age was observed, with physical activity (PA) and basal metabolic rate (BMR) contributing significantly to this decline.
• In elderly patients with diseases, TEE often decreased, primarily due to reduced PA, and sometimes due to decreased BMR.
• Individual variations in TEE were substantial, with differences between individuals accounting for a larger portion of variance than within-individual changes.

Conclusions:

• Aging significantly impacts TEE, with PA and BMR being key contributing factors.
• Chronic diseases in the elderly can exacerbate reductions in TEE, predominantly through decreased physical activity.
• Further research is needed to address potential biases and the complex interplay of diseases on energy expenditure in older adults.