How Many Calories do Runners Really Need?

Long run = license to eat.

Whether that statement is actually true or not it’s absolutely the mindset I hear more often than not from those who come to me confused about why they managed to gain weight while marathon training.

I think it happens subconsciously.

Everyone around us is commenting “oh I bet you can eat whatever you want” and we keep hearing how runners need carbs, so why not have a little more of this and that and that and that and…well you get it.

Let’s get a little sciency today!!

Are you getting enough fuel to keep you running strong? Are you over doing it and thus the scale is slowly creeping up despite your training?

Understanding BMR, RMR and Weight loss

Basal Metabolic Rate and Resting Metabolic Rate are the two most common terms that you might hear about when determining how to calculate calories.

There is a slight difference in the two and it’s important to know which you’re using:

BMR: An estimate of calories burned if you truly laid in bed all day. It accounts for only bodily functions (breathing, etc).

RMR: An estimate of calories burned if you laid in bed all day, but also drank water, ate meals and small activity like moving to the bathroom.

The Harris-Benedict equation for BMR:
For men: (13.75 x w) + (5 x h) – (6.76 x a) + 66
For women: (9.56 x w) + (1.85 x h) – (4.68 x a) + 655
The Mifflin equation for RMR:
For men: (10 x w) + (6.25 x h) – (5 x a) + 5
For women: (10 x w) + (6.25 x h) – (5 x a) – 161
Where:
w = weight in kg
h = height in cm
a = age

In most cases, people will take their RMR + calories burned during exercises to determine the total calorie expenditure for the day.

After finding this, the long held wisdom has been that to lose weight you simply need to keep your calories below this threshold. That’s a debate for another day, but is at least a good place to start with any weight loss program.

GETTING ACCURATE NUMBERS

While both calculations can get you close, an in office test will provide more accurate results to help with weight loss. It’s been stated the Harris Benedict formula can over estimate by up to 24% – YIKES that’s a lot of calories.

Since a BMR test requires an overnight stay in a lab, let’s focus on the more accessible RMR test.

How an RMR test is done?
An RMR test has you sit comfortably with a mask that covers your nose and mouth allowing you to breathe normally. Well normally in that your nose is clipped and you must breathe just through your mouth. For most accurate results you need to fast for 12 hours prior to the test and do as little activity as possible.

How an RMR test works?
For 10 minutes, the machine measures how much oxygen you use while at complete rest to calculate the calorie expenditure of your body.

Where can you do an RMR test?
Lot’s of gyms offer this service as part of the initial package or via a dietitian.

CALORIES BURNED

After getting your RMR results, it’s time to figure out how many calories you are burning through all that running!

While all treadmills come with built in calculators, it’s been reported that these numbers can be up to 30% higher than actual calories burned. SOOOO let’s not even consider that as an option.

Option 1: A heart rate monitor.
This will be one of the most accurate ways to judge calorie burn as it’s truly looking at how hard your body is working based on your age, weight, height and heart rate. I have reviewed a few options like TomTom and Polar.

Option 2: MyFitnessPal
You can simply log your activities in to an online calculator and get a fairly good estimate of calories burned. However long time runners will find the numbers are too high because the longer you do an exercise the more efficient your body becomes and thus…yup less calories burned.

Many runners don’t realize that as they adjust to running farther their body as adjusted too, so they can’t eat as many calories as they used to. BUMMER.

The longer you run, the less you burn! Learn more about how many calories runners need #fitness Click To Tweet

Still with me?! All right the final piece then is:

RMR + activity = total calories burned

None of this is to say running doesn’t give us some extra leeway with our food. But if you’re trying to shed a little body fat or wondering why the same meal plan and miles are suddenly leading to pounds these numbers are a great tool.

Ever have an issue with justifying food because of your workout?

Do you know your numbers?

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