Research

Energy balance

Resting energy expenditure (REE) is determined primarily by the mass of metabolically active organs (brain, liver, heart, kidneys) rather than total fat-free mass or skeletal muscle, as organs constitute only ~5% of body weight but contribute 70-80% of REE.

Your resting calorie burn is driven mostly by your vital organs (liver, brain, heart, kidneys), not your skeletal muscle. While building muscle is healthy, it does not significantly increase your resting metabolic rate compared to the baseline cost of maintaining your organs. Accurate metabolic predictions require measuring organ mass, not just total body weight or muscle size.

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Thus, in adults, 70–80% of REE is derived from organs which comprise only ª5% of body weight (Fig. 2).
Manfred J. Müller et al. · Obesity Reviews · 2002

Why this rating

Based on a compilation of 116 in vivo measurements using precise imaging technologies (MRI/CT), though the paper notes discrepancies between studies.

Source

Metabolically active components of fat‐free mass and resting energy expenditure in humans: recent lessons from imaging technologies

Manfred J. Müller et al. · Obesity Reviews · 2002

DOI 10.1046/j.1467-789x.2002.00057.x

narrative_reviewCited 239×
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DOI resolved against Crossref · corpus check 2026-06-10

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