Basal Metabolic Rate (BMR)
BMR is the name given to the amount of calories our bodies burn in a completely rested state. It is also a measurement of the amount of calories our body needs each day to just function and survive. This means it is made up of the processes in our body that control blood circulation, breathing, controlling body temperature, brain and nerve function and other functions like this that automatically happen. The best way to think about it, if we were to lay in bed and not move at all. Just lay there, breathing and that’s it. This is how many calories our bodies would be expending per day.
If you wish to calculate your BMR there are multiple equations out there, but the most effective one to this day is the “The Mifflin St Jeor equation” [1], below is the formula to work this out.
Male BMR (kcal / day) = ((10 * weight (kg)) + (6.25 * height (cm)) – (5 * age (years)) + 5) Female BMR (kcal / day) = ((10 * weight (kg)) + (6.25 * height (cm)) – (5 * age (years)) -161)
Total Daily Energy Expenditure (TDEE)
Your TDEE is the total number of calories that your body expends in a day. This encompasses all activities, not just meaningful exercise. Even though walking is something we do without thinking about it is still included. Working out your TDEE is relatively simple. We take your BMR you worked out above and then use a multiplier to get your estimated TDEE. It is worth nothing that these are never going to be 100% accurate but will be a good place to start.
Sedentary = BMR x 1.2 (little or no exercise, desk job) Lightly active = BMR x 1.375 (light exercise/ sports 1-3 days/week) Moderately active = BMR x 1.55 (moderate exercise/ sports 6-7 days/week) Very active = BMR x 1.725 (hard exercise every day, or exercising 2 xs/day) Extra active = BMR x 1.9 (hard exercise 2 or more times per day, or training for marathon, or triathlon, etc. I will also note that people will generally overestimate what their activity levels actually are. For the majority of people they will be in the lightly active range, this isn’t saying you don’t train hard, its just that these multipliers scale up quite quickly. Your TDEE is also comprised of 4 different things to get that total caloric expenditure. Thermic effect of food (TEF) 8–15% Exercise activity thermogenesis (EAT) 15–30% Non-exercise activity thermogenesis (NEAT) 15–50% Basal metabolic rate (BMR) 60–70%
Non Exercise Activity Thermogenesis (NEAT)
NEAT is something that is quite hard to measure outside of a lab environment. What your NEAT is comprised of is any sort of activity that isn’t sleeping, food or sports like exercise (weight training, sports etc). This means that just walking around, waving your hands when talking, blinking even. Everything like that compromises your daily NEAT. This is why we encourage people to increase their NEAT. Outside of BMR, your NEAT is the next biggest contributor to your total daily expenditure. By increasing your NEAT (by just being more active in general), this will go a long way to increasing your daily energy expenditure which will then assist with weight loss.
Exercise-associated Thermogenesis (EAT)
EAT is something which you won’t see too much, but it is the calories burned through intentional exercise. Devices like fitbits can be used to track the amount of calories burned through exercise, but due to multiple factors like sex, age, weight, type of exercise (anaerobic vs aerobic), type of tracking device as well as placement position on the body, the results can vary and are not reliable from a tracking point of view [2].
Thermic Effect of Food (TEF)
This term you may have heard on social media. TEF refers to the calories your body burns when attempting to break down food. As of writing this there is no real way to measure this outside of a Metabolic Ward. There is a good myth out there of “negative calorie foods”, foods that when consumed cause the body to burn more calories than the food contains. This has however been shown to be just another myth that won’t go away [3], [4]
References
[1] Frankenfield D, Roth-Yousey L, Compher C (2005). "Comparison of predictive equations for resting metabolic rate in healthy, nonobese and obese adults: A systematic review". Journal of the American Dietetic Association. 105 (5): 775–789. doi:10.1016/j.jada.2005.02.005. PMID 15883556.
[2] Feehan LM, Geldman J, Sayre EC, et al. Accuracy of Fitbit Devices: Systematic Review and Narrative Syntheses of Quantitative Data. JMIR Mhealth Uhealth. 2018;6(8):e10527. Published 2018 Aug 9. doi:10.2196/10527 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6107736/
[3] Negative calorie foods: An empirical examination of what is fact or fiction
Katherine M. Buddemeyer, Ashley E. Alexander, Stephen M. Secor
bioRxiv 586958; doi: https://doi.org/10.1101/586958, https://www.biorxiv.org/content/10.1101/586958v1.abstract
[4] Rezaeipour M, Apanasenko GL, Nychyporuk VI. Investigating the effects of negative-calorie diet compared with low-calorie diet under exercise conditions on weight loss and lipid profile in overweight/obese middle-aged and older men. Turk J Med Sci. 2014;44(5):792-8. doi: 10.3906/sag-1303-10. PMID: 25539547. https://pubmed.ncbi.nlm.nih.gov/25539547/
Article written by Timothy Steward
· UFQ Strength & Conditioning Coach
· UFQ Sports Nutritionist