Research

Energy balance

Total energy expenditure (TEE) and physical activity level (PAL) decline progressively throughout adult life (from age 20 to 96) in both normal weight and overweight individuals, primarily driven by a decrease in physical activity rather than just basal metabolic rate changes.

As you age, your body burns fewer calories, but this isn't just because your organs slow down. A large part of the drop comes from moving less (lower Physical Activity Level). To maintain your weight, you need to account for this gradual decline in energy expenditure (about 150 kcal/day less per decade for normal-weight adults) by adjusting your food intake or increasing your physical activity levels.

GoodSupportsHIGH confidence
TEE and physical activity level (PAL, defined as the ratio of total to resting energy expenditure) declined progressively throughout adult life in both normal weight and overweight men and women... In normal weight individuals... TEE fell by < 150 kcal per decade, and PAL fell from an average of 1.75 in the second decade of life to 1.28 in the ninth decade.
Susan B. Roberts et al. · Public Health Nutrition · 2005

Why this rating

Based on a large database (802 data points from 122 studies) using the doubly labelled water method, though cross-sectional and lacking developing country data.

Source

Energy requirements and aging

Susan B. Roberts et al. · Public Health Nutrition · 2005

DOI 10.1079/phn2005794

narrative_review · n=802Cited 168×
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DOI resolved against Crossref · corpus check 2026-06-10

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