Alex asked me an interesting question in the comments, namely: How can I calculate my calories burned during a workout? Can I do it if I know my heart rate (from wearing a heart rate monitor)?
Well, Alex. That is a very good question with a very long answer. Hence, a whole post – just for you! Everyone else feel free to close their ears. Unless you have more info on this subject than I do (Andrew? You out there??) – then, by all means, SHARE!
Calculating Your Basal Metabolic Rate
Your BMR, otherwise known as how many calories your body burns just to survive (so not counting exercise), is the place to start. You have to know how many you need to know if you have a deficit or not.
The only really accurate way to calculate this is to pay a lot of $$$ and get a metabolic testing done (they offer these, with varying accuracy, at many gyms nationwide). The next best thing is to use one of the BMR formulas. There are three main ones, with the Katch-McArdle being the most accurate (but you have to know your lean muscle mass, derived from your body fat %). Tom Venuto, one of my heroes & my first real introduction into nutrition and fitness, puts it much better than I can. Check out all the formulas here.
If you are bad at math, or just lazy, here’s a quickie calculator for you.
Calories Burned in Exercise
This is what Alex was asking me. How to tell how many calories you burned during exercise? If you have a heart rate monitor that does this for you, then the only trick is figuring out how to use said heart rate monitor (which can get your heart rate up just by reading the friggin’ manual). You should know that each heart rate monitor (whether it be on your wrist or on your elliptical) uses a proprietary formula to calculate calorie burn based on, at minimum, your weight and heart rate. The good ones will also factor in your gender, height and age. Each company (Polar, Timex etc.) has their own formulas they’ve developed and they’re not happy about sharing them. Probably because someone would actually do the math and realize that they are overestimating your calories for material gain. Ahem.
So, what’s a fitness fiend to do? There are plenty of online calculators that will estimate your calorie burn based off of type of activity, weight, duration and perceived exertion. I particularly like the one on Self.com
You will notice though that there is nowhere to put in your heart rate, even if you know it. This is because your heart rate is constantly changing during your workout and so this information isn’t helpful to you in this context. Even if you know your average heart rate, the formulas are already based on averages so your won’t be so much different. You can use your heart rate though to gauge your perceived exertion over time.
Hope this helps, Alex! If any of you have anything to add- please jump in!