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Nutrition

Resting metabolic rate (RMR / BMR)

The calories your body burns at complete rest to keep organs, breathing, and body temperature running — the biggest slice of daily energy expenditure.

By the glp1.how editorial teamReviewed

Resting metabolic rate (RMR) is the energy your body uses when you're doing nothing at all — keeping your heart beating, lungs breathing, brain working, and body temperature steady. Basal metabolic rate (BMR) is a slightly stricter laboratory version measured under controlled conditions; in everyday use the two terms are close enough to be interchangeable. RMR is normally the largest component of total daily energy expenditure, with the rest coming from digestion, daily movement, and exercise.

It matters on a GLP-1 because RMR is largely set by how much lean tissue you carry. As weight comes off — especially if muscle comes off with it — RMR drops, and it can drop a little further than body size alone predicts (adaptive thermogenesis). That's why protecting muscle with protein and resistance training, and re-checking calorie targets as you lose weight, both matter. See calories in, calories out on a GLP-1 and do TDEE calculators still work after big weight loss. A 2021 review describes how losing lean tissue lowers energy expenditure and how adaptive thermogenesis pushes resting expenditure down further (Egan and Collins, 2021 (external link)).

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Related terms

  • TDEE (total daily energy expenditure) · The total number of calories your body burns in a day, combining resting metabolism, digestion, everyday movement, and exercise.
  • Adaptive thermogenesis · A larger-than-expected drop in the calories your body burns during weight loss, beyond what the loss of body mass alone would predict.
  • GLP-1 · A gut hormone (glucagon-like peptide-1) that stimulates insulin release, slows digestion, and reduces appetite; the target of drugs like semaglutide and liraglutide.
  • Resistance training (progressive overload) · Exercise that loads your muscles against resistance and is made gradually harder over time (progressive overload) to keep or build muscle and strength.

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