Basal metabolic rate
Also called: BMR, resting metabolic rate
Clinical reviewer: Jacob Moore, MD · Last checked September 24, 2026
What is basal metabolic rate?
Basal metabolic rate is the energy the body uses at complete rest to keep basic functions running, the largest component of daily energy demand in Western societies. It is shaped mainly by differences in fat-free mass, with smaller contributions from fat mass and age.
What determines basal metabolic rate?
Basal metabolic rate is the energy the body uses at complete rest to keep basic functions running. It is the largest component of daily energy demand in Western societies [1]. In a study of 150 adults in northeast Scotland, differences in fat-free mass explained 63% of the variation in basal metabolic rate between people, fat mass explained another 6%, and age about 2%, leaving 26% of the variation unexplained; sex and bone mineral content were not significant factors [1].
Does basal metabolic rate change with weight loss, or with GLP-1 treatment?
In a follow-up of 14 "Biggest Loser" contestants, resting metabolic rate had fallen by an average of 610 kcal/day by the end of the competition, and was still 704 kcal/day below baseline six years later; after adjusting for body composition and age, the researchers concluded that this metabolic adaptation persists and is likely a proportional, but incomplete, response to efforts to reduce weight [2]. In a 12-week trial of 30 adults with obesity, resting metabolic rate, adjusted for lean body mass, did not differ between semaglutide and placebo [3].
Related terms
Sources
- Factors influencing variation in basal metabolic rate include fat-free mass, fat mass, age, and circulating thyroxine but not sex, circulating leptin, or triiodothyronine.
- Persistent metabolic adaptation 6 years after "The Biggest Loser" competition.
- Effects of once-weekly semaglutide on appetite, energy intake, control of eating, food preference and body weight in subjects with obesity.
This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
