Diet junk-food

Published on May 6th, 2013 | by James Fell


How Much Exercise Does it Take to Burn off Junk Food?

Many say they’d be less likely to eat junk if a label showed how much exercise it takes to burn off. There is just one problem with that idea.

You know what I hate? I hate that, “If I can do it, so can you” motivational pablum. It’s a load of crap. I exercise my ass off and eat a mostly healthy diet (plus beer), and it’s a fact that most people in the world can’t do this. I mean, go to Wal-Mart and have a look around if you doubt me.

But if I can do it, so can you.

Wait, what? Oh, I’m actually not talking about diet and exercise. I’m talking about math. I suck at math. All through school I scraped through on that subject.

This post is about math, and yes, considering how much I suck, I am comfortable in saying that if I can do it, so can you.

The problem with “exercise counts” of food packages

There is a new study by the Federation of American Societies for the Study of Experimental Biology that says “exercise amount” may do a better job of deterring excess calorie intake than actually labelling the amount of calories on food.

In other words, if that blueberry muffin is represented as an hour of brisk walking instead of 300 calories, you’ll be less likely to eat it.

But here’s the problem, and it’s ones that I’ve been railing against for years: calorie burning is VERY individual. The bigger you are, the more calories you burn, sitting, walking, running or lifting weights. Height and age are factors as well. A young, tall, heavy person will burn way more calories per hour than an older, leaner, shorter person will. Gender is another way in which metabolism differs; men burn more calories than women do.

And that’s why any kind of list of “how much exercise to burn off whatever snack” is going to be faulty if it doesn’t account for these individual differences. You’re going to want to grab a calculator before you go any further, or maybe get an Excel (ARGH! Hate it so much!) spreadsheet going. Here is how to get started.

Step 1 – Go Metric

Even though I’m Canadian, I won’t rag on Americans for still using imperial measurements, because I’m six feet tall, and if I want to know my height in centimetres or weight in kilograms, I need to dig out my driver’s license.

The formula for these equations uses metric. So suck it up. It gets harder after this. Get the numbers for these two things:

  • Your weight in pounds divided by 2.2 = Your weight in kilograms
  • Your height in inches multiplied by 2.54 = Your height in centimeters

Calculate Your Resting Metabolic Rate

Now that you have those two numbers, you’re ready to calculate your resting metabolic rate (RMR) using what is called the Mifflin equation. IMPORTANT: Remember your basic rules of math – Calculations inside the brackets are done first.

Women use this formula

(10 X weight in kilograms) + (6.25 X height in centimeters) – (5 X age) – 161 = RMR

Men use this formula

(10 X weight in kilograms) + (6.25 X height in centimetres) – (5 X age) + 5 = RMR

Let’s do mine. Since I’m a guy, I’ll be using the second equation. I weigh 77.3 kg (170 pounds), am 183 cm (6 feet even) and 45-years old. Therefore:

773 (my weight in kg X 10) + 1143.75 (6.25 X my height) – 225 (5 X my age) + 5 = 1697 Calories per day burned via RMR.

So what is this RMR number you now have?

It’s how many calories you burn each day being completely sedentary. It doesn’t account for any other calories you burn via general activity, sport, or digestion. It also doesn’t account for differences in body composition. A person with less fat and more muscle will have a higher metabolism (although not nearly as much as you might think). I’ll stress here that the RMR you get from this calculation still involves guesswork. It’s pretty accurate, but there are a host of ways in which people can differ metabolically, including due to medical conditions and/or medication.

But it’s what we’ve got, and it’s going to have to fall into the category of “good enough.”

Why is RMR important to this subject of how much exercise to burn off a snack? Well, to really drive it home, we need to do one final calculation.

Take that RMR Number, and Divide by 24

Why? Well, so you can know how many calories you burn while sitting on your ass each hour. That’s why.

For me, the answer comes out close enough to 70 calories per hour, sitting here at my computer, writing this article.

It is a very valuable tool for you to know how many calories you burn each hour while being sedentary, because then you know how many your burn each hour while active.

If you’re a smaller woman, the number may be 50 calories per hour. For a bigger guy, it can be 100. The differences can be even greater than this. See why it’s so important to do the equations to account for individual metabolism?

Here is what happens when you start moving:

  • Light or moderate weightlifting = Increases RMR by 3
  • Walk briskly (4mph) = Increases RMR by 5
  • Low impact aerobics class = Increases RMR by 5
  • Lift weights intensely = Increases RMR by 6
  • Cycling at 12-14mph = Increases RMR by 8
  • Running at 6mph = Increases RMR by 10
  • Fast swimming = Increases RMR by 10
  • Running at 8mph = Increases RMR by 13.5

The above was adapted from Essentials of Strength Training and Conditioning, 3rd Edition.

Those are just a few examples to give you a guideline. So say you’re on the smaller side and your sedentary RMR is 50 calories per hour. Like I stated above, the light weights burns 150 calories per hour, a brisk walk burns 250 calories per hour, cycling at 12-14mph burns 400 calories per hour, and fast swimming burns 500 calories per hour. If you’re bigger and your per hour RMR is 100 calories, then all those numbers would be doubled.

See how this is all not just based on the individual, but the exercise and the intensity?

Wait, there is one more final, killjoy calculation.

Everything up there doesn’t account for EXTRA calories. This hypothetical person burns 50 calories just sitting around. If she runs for an hour at 6mph then she burned 500 total calories, but since should would have burned 50 doing nothing, the extra burn drops to 450. The reason why I consider this important is that, at a minimum, she’d burn off those 50 calories anyway. So if she’s considering extra treats like doughnuts that are outside her normal eating regimen, then she needs to consider extra activity like running that is outside her normal “sitting on her ass” regimen.

Yes, as the study pointed out, people may be more motivated to eat snacks if the label says how much exercise it translates to, but the problem is that any such label is going to be terribly inaccurate. If you’re a stickler for accuracy, then you need to do these calculations. Also, since caloric labelling IS prevalent, and “exercise labelling” is not, then it’s pretty much a must-do if you want to have any idea of what it takes to burn off certain foods.

And it is worth crunching the numbers. While I’m not a fan of counting calories in and out each day, these types of calculations can increase your “caloric awareness,” and make resisting certain treats a lot easier. If you look at a plate of nachos, knowing it’s dripping with a thousand greasy calories, understanding just how many hours of fast running it’s going to take to burn off may make you think twice about eating it.

My final advice is this: understand what it takes to burn off a certain treat, and then decide if it’s worth it. Everyone deserves indulgence, but if it is something that packs a lot of calories, yet only tastes so-so, knowing what it takes to burn it off can make such indulgences rare instead of commonplace.

If you want a lot more detailed information on metabolism and how it works, get your FREE REPORT here.

James S. Fell, CSCS, is the co-founder of James is a nationally syndicated fitness columnist for the Chicago Tribune and Los Angeles Times. His book, Lose It Right: A Brutally Honest 3-Stage Program to Lose Weight Without Losing Your Mind is coming from Random House in Fall, 2013.

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