Research

Energy balance

Caloric restriction in normal-weight men reduces basal metabolic rate (BMR) by approximately 15% over 21 days, independent of the amount of lean mass lost.

When you restrict calories, your resting energy expenditure drops significantly (by ~15% in this study). This drop is not strictly tied to how much muscle you lose, suggesting a general metabolic slowdown to conserve energy.

GoodSupportsHIGH confidence
BMR declined from 1,898 ± 262 to 1,670 ± 203 kcal/day... No significant association was observed between quantity of weight or lean mass lost and decline in BMR among individual subjects.
Anne L. Friedlander et al. · American Journal of Physiology-Endocrinology and Metabolism · 2005

Why this rating

Controlled study with direct calorimetry measurements.

Source

Three weeks of caloric restriction alters protein metabolism in normal-weight, young men

Anne L. Friedlander et al. · American Journal of Physiology-Endocrinology and Metabolism · 2005

DOI 10.1152/ajpendo.00001.2005

crossover · n=9Cited 57×
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DOI resolved against Crossref · corpus check 2026-06-10

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