“Building muscle boosts your metabolism.”
Muscle does burn more calories at rest than fat, but the boost from the muscle people realistically build is tiny.
Lift for strength, for the way you look and move, and for keeping muscle when you lose weight, not to turn your body into a calorie furnace. A gain of 10 to 100 calories a day at rest is easy to cancel with a snack, so the metabolism bump cannot stand in for eating a little less.
Lift two or three times a week, and count the metabolism bump as a bonus rather than the plan.
Measured tissue rates show muscle burns about 6 calories per pound a day at rest, so the 2 pounds or so of muscle people realistically add is worth only about 10 calories a day. Lifting as an activity raises resting burn by about 96 calories a day in trials, but those trials are small and low quality, so the exact size is uncertain.
Muscle does burn more calories at rest than fat, but the boost from the muscle people realistically build is tiny. Each pound of muscle burns about 6 calories a day at rest, so the 2 pounds or so that months of lifting typically adds is worth about 10 calories a day, and the popular claim of 50 calories per pound is about eight times too high. In the trials, the biggest fat loss came from pairing lifting with eating less: lifting plus a calorie deficit took off about 12 pounds of fat with muscle held steady, compared with about 2 pounds of fat for lifting alone.
Measurements in 131 adults found resting muscle burns about 6 calories per pound a day, compared with about 2 calories per pound for fat tissue. Across 114 trials in adults with overweight or obesity, lifting programs added about 2 pounds of muscle. Trials that measured resting metabolic rate before and after months of lifting found a rise of about 96 calories a day, more than the new muscle alone would explain, likely from the ongoing work of repair and recovery. Cardio training did not raise resting metabolic rate by a clear amount in the same analysis.
Small daily differences in eating easily outweigh a metabolism change of this size. Adults in national surveys reported eating about 1,955 calories a day in 1971 to 1975 and about 2,195 in 2009 to 2010, a rise of about 240 calories a day. In trials of exercise training in adults with overweight, intake rose by about 100 calories a day compared with people who did not exercise.
Does lifting raise your resting metabolism at all?
Yes. Across trials, resistance training raised resting metabolic rate by about 96 calories a day, on top of the calories burned during each session. The studies were low quality, and some people eat part of the extra burn back, but the effect is real and worth having.
- Wang Z, Ying Z, Bosy-Westphal A, et al. Specific metabolic rates of major organs and tissues across adulthood: evaluation by mechanistic model of resting energy expenditure. Am J Clin Nutr. 2010;92(6):1369-1377. DOI: 10.3945/ajcn.2010.29885. PMID: 20962155
- MacKenzie-Shalders K, Kelly JT, So D, Coffey VG, Byrne NM. The effect of exercise interventions on resting metabolic rate: a systematic review and meta-analysis. J Sports Sci. 2020;38(14):1635-1649. DOI: 10.1080/02640414.2020.1754716. PMID: 32397898
- Lopez P, Taaffe DR, Galvao DA, et al. Resistance training effectiveness on body composition and body weight outcomes in individuals with overweight and obesity across the lifespan: a systematic review and meta-analysis. Obes Rev. 2022;23(5):e13428. DOI: 10.1111/obr.13428. PMID: 35191588
- Ford ES, Dietz WH. Trends in energy intake among adults in the United States: findings from NHANES. Am J Clin Nutr. 2013;97(4):848-853. DOI: 10.3945/ajcn.112.052662. PMID: 23426032
- Beaulieu K, Blundell JE, van Baak MA, et al. Effect of exercise training interventions on energy intake and appetite control in adults with overweight or obesity: a systematic review and meta-analysis. Obes Rev. 2021;22(Suppl 4):e13251. DOI: 10.1111/obr.13251. PMID: 33949089