BMR Calculator
Guide

How to increase your BMR

What can genuinely raise your basal metabolic rate, how large the effect is, and which popular claims do not change BMR.

Short answer

The main thing you can change is the amount of fat-free mass, especially muscle, that you carry. In controlled studies, resistance training raised resting metabolic rate by about 96 kcal/day on average compared with control groups. That is real but modest. Most other popular “metabolism boosters” either do not change BMR or affect a different part of daily energy use.

What sets your BMR

Resting energy use is driven mainly by body size and fat-free mass: muscle, organs, bone and water. That is why larger people and people with more muscle tend to have a higher BMR, and why prediction equations use weight, height, age and sex. Fat-free mass is such a strong predictor that the Cunningham equation estimates resting energy from fat-free mass alone.

1. Build or keep muscle with resistance training

A 2020 systematic review and meta-analysis of exercise trials found that resistance training increased resting metabolic rate compared with control groups by an average of 96 kcal/day (95% confidence interval 45 to 147 kcal/day). Aerobic training alone did not produce a statistically significant change in that analysis.

Two cautions: the studies varied a lot in design and many had a high risk of bias, and the effect depends on actually gaining or keeping fat-free mass over months. Training of any kind also raises total daily energy use through the activity itself, which is a separate effect from BMR.

2. Protect muscle when losing weight

Losing weight lowers BMR, mostly because a smaller body needs less energy. Studies have also observed adaptive thermogenesis, a further drop beyond what the lost tissue explains, although its size varies widely between people and studies.

Resistance training during weight loss helps keep fat-free mass. In a meta-analysis of six randomized trials in older adults with obesity, calorie restriction alone led to an average lean-mass loss of about 0.8 kg, while calorie restriction combined with resistance training prevented almost all of that loss. Keeping lean mass limits the part of the BMR drop that comes from losing muscle.

3. Understand what age does and does not do

A large 2021 study of measured energy expenditure across the lifespan found that total and basal expenditure, along with fat-free mass, were stable from about age 20 to 60. After adjusting for body size and composition, total expenditure began declining at around 63, by about 0.7% per year. Adjusted basal expenditure may begin declining earlier, but that estimate was less certain because few basal measurements were available for ages 45–65.

In practice, much of the “metabolism slows in middle age” idea reflects changes in body composition and activity rather than an automatic drop at 30 or 40. Keeping muscle and staying active are the levers you control.

What does not raise BMR

  • Specific foods and eating more often. Digesting food uses energy (the thermic effect of food), but that is counted as a separate part of daily expenditure, not BMR. Changing meal timing or eating particular foods does not change your basal rate.
  • Cardio as a BMR booster. Aerobic exercise is valuable for health and burns energy while you do it, but the meta-analysis above did not find a significant effect on resting metabolic rate.
  • Severe calorie restriction. Very low intake drives weight loss that includes muscle and can be accompanied by adaptive thermogenesis, both of which lower resting energy use.
  • “Metabolism-boosting” supplements. None is needed to raise BMR in a meaningful, lasting way. Products sold for this purpose can carry health risks, so check with a doctor or pharmacist before using them.

When a low metabolic rate may be medical

Some medical conditions and medicines can change energy expenditure. If you have symptoms such as unexplained weight change, persistent tiredness or feeling cold, talk to a doctor rather than trying to raise your metabolism on your own. A calculator estimate cannot detect a medical problem; a clinician can order tests, and indirect calorimetry can measure resting expenditure directly when that matters.

See your numbers

Use the BMR calculator for your own estimate, and compare it with the average BMR for your age and sex. Remember that a lower-than-average estimate usually reflects a smaller body rather than a slow metabolism.

Sources

  1. 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. PMID 32397898.
  2. Pontzer H, Yamada Y, Sagayama H, et al. Daily energy expenditure through the human life course. Science. 2021;373(6556):808-812. PMID 34385400 / PMC full text.
  3. Cunningham JJ. Body composition as a determinant of energy expenditure: a synthetic review and a proposed general prediction equation. Am J Clin Nutr. 1991;54(6):963-969. PMID 1957828.
  4. Nunes CL, et al. Does adaptive thermogenesis occur after weight loss in adults? A systematic review. Br J Nutr. 2022;127(3):451-469. PMID 33762040.
  5. Sardeli AV, Komatsu TR, Mori MA, Gáspari AF, Chacon-Mikahil MPT. Resistance training prevents muscle loss induced by caloric restriction in obese elderly individuals: a systematic review and meta-analysis. Nutrients. 2018;10(4):423. doi:10.3390/nu10040423.
  6. National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy. 2023. Chapter 4: Factors Affecting Energy Expenditure and Requirements. NCBI Bookshelf.

Educational information only, not medical advice.