How Many Calories Do You Burn Daily?

To the outside world we runners seem like indomitably healthy people. We exercise a lot, we’re in tune with our biomechanics and we eat right all the time…right? Wink wink. Nudge nudge.

You and I know the dirty little secret; that so many of us run so we can eat (or drink) whatever we want. If you’ve ever trained for a marathon you know that bottomless-pit feeling that allows pizza to be accompanied by weight loss. But when the marathon is over or when you’re sidelined by injury it’s important to know your body’s baseline when it comes to fuel.ย  When you’re armed with the right information you can check in with your diet from time to time to make sure you’re on track to continue improving your athletic body composition.

To start, figure out how many calories your metabolism can handle on a daily basis apart from running. To estimate that number, you can use the Harris-Benedict equation, which calls that number your Basal Metabolic Rate, or BMR. Now we’re going to get into some math here, but don’t be intimidated! I promise it’s easy once you break it down, and it’s fun to figure out where you stand!

For women, the BMR formula goes like this:

“That’s 4.35 x 110 and then what’s 7’2″ in inches?” Image via NY Times.

655 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)

So, for a 153 pound woman like me, who is 5’5″ (65″) and 31 it goes like this:

655 + (4.35 x 153) + (4.7 x 65) – (4.7 x 31)

And then we break it down step by step, just like in math class (except I’ll let you use a calculator):

655 + (665.55) + (305.5) – (145.7) = 1470.35

*If you’re a fella, or if you dig on the metric system you can find the appropriate formula here.

So my Basal Metabolic Rate is about 1470 calories. That’s a whole lot less than the “standard” 2000 calorie-a-day diet upon which the nutritional info on my cereal box is based! The reality looks a little different when you calculate in daily activity level (again, this is your normal all-day activity, so your running doesn’t count unless you do it all day long).

Next we take our BMR and adjust it for our lifestyles:

Personally, I think it’s better to track your activity for a week using a pedometer or an online tool or app, but since we’re using it, here’s what the Harris-Benedict equation uses to estimate your daily caloric needs:

Sedentary (little or no exercise, like office workers, drivers and those who lounge on divans all day), multiply BMR x 1.2

This lady should probably skip the bon-bons if she wants to maintain her perfect Romanesque physique. Image via fineartamerica.com

Lightly active (light exercise, like yard work a few days a week or someone who works in retail), multiply BMR x 1.375

Moderately active (moderate exercise, like waitresses or other people who walk a lot at work, mothers of small children, etc), multiply BMR x 1.55

Very active (hard exercise 6-7 days a week, like landscapers with waitressing gigs on the side and small children), multiply BMR x 1.725

The resulting number will be your Active Metabolic Rate, or AMR. Since I’m a New Yorker (I walk a lot) and I work on my feet all day I’m going to say I’m moderately active. So I’ll take my BMI of 1470 and multiply it by 1.55, which gives me an AMR of 2,278.

Theoretically if I eat significantly fewer calories than 2278, I will lose mass. If I eat lots more I will gain. If I stick in the 2200 range I will maintain my current mass.

And now to determine how many calories you need based on your exercise on top ofย your daily activities:

For runners, you can figure out what activity level you meet in your non-running life. For example, Salty is the mother of two small very mobile children so she’d be in the Moderately Active category (we’ll just pretend she’s not pregnant for this example!). Say she weighs 130 and is 5’4″. So before running she needs about 2,300 calories per day to maintain her weight.

Then determine how many calories you’re burning each week from running. A good rule of thumb is 100 calories per mile. If Salty’s running 50 miles per week she’s burning about 5000 calories per week from running or ~700 per day. So she’d probably need close to 3,000 calories a day to stay at 130!

A few caveats:

Hi! Let me calculate your daily caloric needs and then make you do so many planks your shoulders catch on fire. Image via gettingfit.com

Remember that these numbers are estimations only! If you want more accurate measurements, check with a physician or your local gym or a personal trainer.

It’s also important to note that these calculation assumes a “normal” body composition, meaning an optimal fat-to-muscle ratio. If we’re being honest here I have a higher fat level than is optimal, so for my body we need to adjust this number lower. If you have a lower fat level than is optimal, meaning more muscle, you will need to adjust this number higher. I basically just calculate my AMR at the activity level lower than my own (which puts me at 2021 calories daily, which seems to work for me to maintain my current size.

But now that you know your baseline you can make more educated decisions about fueling your body. You know where you stand on your rest days or when you need some time off from running, and you can be mindful of ensuring you meet your body’s needs after a 700-calorie 7 mile run! And if you want to drop or add a couple pounds for a race you can adjust your calorie intake accordingly as well.

Do you monitor your caloric intake? What’s your AMR?

Cinnamon made Salty Running, works on movies and TV and drinks lots of coffee. She is on a quest for zen in the 10k. Her writing is an eclectic mix of finding wholeness as an average runner, celebrating her faster peers, curious reactions, satirical humor and more.