Boosting Your Metabolism: How to Speed It Up, and What Is Not Proven
Quick answer: For "boosting your metabolism": basal metabolic rate (BMR) is the energy your body uses at complete rest. The Mifflin-St Jeor equation estimates it as 10 x weight (kg) + 6.25 x height (cm) - 5 x age + 5 for men or - 161 for women. This is general information, not medical advice.
Last updated: October 2026. We quote no live prices; facts come from the sources listed and may have changed; worked numbers are invented.
Background
Basal metabolic rate, usually shortened to BMR, is the amount of energy your body needs at complete rest to keep you alive: to breathe, circulate blood, maintain body temperature and run the brain and organs. Strictly, BMR is measured after a night's sleep, fasted and in a comfortable temperature, while resting metabolic rate (RMR) is measured under looser conditions and is usually a little higher. For most people the two figures are close, and the terms are often used loosely.
BMR is commonly cited as making up roughly 60 to 70 per cent of total daily energy use in many adults, with the rest coming from physical activity and from the energy used to digest food. It varies with body size, body composition (lean tissue uses more energy than fat tissue), age, sex, genetics, hormones such as thyroid hormones, and temperature. It tends to fall with age, partly because of the loss of lean mass.
The abbreviation BMR is also used by Groupe BMR, a Quebec building-materials and hardware network, as we understand it. If you searched for that business, this article is not about it, and you should use the retailer's own site for stores and flyers.
What to check and how to decide
Two formulas are widely used to estimate BMR from weight in kilograms, height in centimetres and age in years. The Mifflin-St Jeor equation, published in 1990, gives BMR = 10 x weight + 6.25 x height - 5 x age + 5 for men and 10 x weight + 6.25 x height - 5 x age - 161 for women. The revised Harris-Benedict equation (Roza and Shizgal, 1984) gives, for men, 88.362 + 13.397 x weight + 4.799 x height - 5.677 x age, and for women, 447.593 + 9.247 x weight + 3.098 x height - 4.330 x age. Studies generally find Mifflin-St Jeor to be a good estimate for many adults, but any formula can be off by a noticeable margin for an individual.
A worked example, with invented numbers: a 35-year-old woman who weighs 65 kg and is 165 cm tall has a Mifflin-St Jeor estimate of 650 + 1,031.25 - 175 - 161 = about 1,345 kilocalories per day. A 40-year-old man who weighs 80 kg and is 180 cm tall gets 800 + 1,125 - 200 + 5 = 1,730 kilocalories per day. These are examples to show the arithmetic, not data about any real person.
To estimate total daily energy needs, nutrition calculators multiply BMR by an activity factor, commonly about 1.2 for a sedentary day, 1.375 for light activity, 1.55 for moderate activity and 1.725 for very active days. The result is an estimate, not a target, and a registered dietitian or doctor can give personal advice. The gold standard for measuring metabolic rate is indirect calorimetry in a clinic, which measures oxygen use and carbon dioxide output.
| Item | What it means |
|---|---|
| Mifflin-St Jeor (1990) | Weight, height, age, sex; widely used |
| Harris-Benedict, revised (1984) | Same inputs; older, often overestimates |
| Activity factor | Multiplies BMR to estimate daily needs |
| Indirect calorimetry | Clinical measurement; most accurate |
Common mistakes with metabolic-rate estimates
The first mistake is treating a calculator result as a precise measurement. Every equation is built from averages across groups of people, so an individual's true resting metabolic rate can differ by a couple of hundred kilocalories in either direction. Use the number as a starting point, track your own weight, energy and hunger over several weeks, and adjust gradually, not drastically.
The second mistake is confusing BMR with a daily calorie target. BMR covers only the energy used at rest. Your total daily energy use also includes movement and the energy needed to digest food, and a target for weight change depends on your goals, health and medical advice. Eating far below your estimated BMR for long periods is not generally recommended without supervision.
The third mistake is believing quick-fix claims. Products and programmes that promise to "reset" or "supercharge" metabolism rarely have solid evidence behind them. Sleep, resistance training, adequate protein and consistent activity have the best general support, but individual needs differ, and a registered dietitian or doctor can tailor advice to you.
- Use the calculator only as a starting estimate
- Do not eat below BMR without professional advice
- Track real-world results over weeks
- Be wary of supplements that promise to boost metabolism
- Include strength training and sleep in the plan
- Ask a dietitian or doctor for personal advice
Using the numbers in daily life
If you want a practical approach, start by estimating BMR, multiply it by an honest activity factor, and treat the result as a rough maintenance level. Weigh yourself under consistent conditions, for example in the morning before eating, and look at the weekly average, not a single reading. If weight is stable, you are roughly at maintenance; if it rises or falls steadily, adjust intake or activity in small steps.
Remember that metabolic needs change with life events. Pregnancy, illness, medication, ageing and changes in muscle mass can all shift them. People with thyroid conditions, diabetes or eating-disorder histories should take advice from a clinician before using any calorie target.
Consumer tips and alternatives
Treat any online BMR calculator or smart-scale reading as a rough estimate. Smart scales and fitness watches estimate body composition and metabolic rate with built-in formulas, and errors of ten per cent or more are common. Do not set a very low calorie target from a single number, and speak to a doctor or registered dietitian before major dietary changes, especially if you are pregnant, have a medical condition or take medication.
Claims that a supplement, tea or trick can dramatically "boost" metabolism are mostly unproven, and some products carry health risks. What has the best support is ordinary: building and keeping muscle through resistance training, eating enough protein and enough food overall, sleeping well and staying active through the day. Extreme dieting can reduce metabolic rate rather than raise it. Health Canada's Canada's Food Guide offers general healthy-eating advice.
Health and fitness apps collect sensitive personal data. In Canada the Personal Information Protection and Electronic Documents Act (PIPEDA) governs how private-sector organisations handle personal information, so read an app's privacy policy and avoid sharing more than you need.
Check, compare and keep records. Those three habits protect you whichever store you are dealing with, and they cost nothing. Remember that Canadian shelf prices usually exclude GST or HST and provincial sales tax, so the till total is higher, and that in Quebec stores must offer French-language service and labelling.
Frequently asked questions
What does BMR mean?
Basal metabolic rate: the energy your body uses at complete rest.
Which formula is best?
Mifflin-St Jeor is widely used for adults, but any formula is an estimate; a clinic can measure it directly.
Is this medical advice?
No; speak to a doctor or registered dietitian before changing your diet.
Sources
- Mifflin MD, St Jeor ST et al., 'A new predictive equation for resting energy expenditure in healthy individuals', American Journal of Clinical Nutrition, 1990
- Roza AM, Shizgal HM, 'The Harris Benedict equation reevaluated', American Journal of Clinical Nutrition, 1984
- Health Canada, Canada's Food Guide (food-guide.canada.ca)
- Dietitians of Canada (dietitians.ca)
