Does It Really Matter How Many Calories Your Workout Burns? [The problem with heart rate monitors]

by Charlotte on May 8, 2013 · 43 comments


This “super slimmer” face mask from japan claims to burn calories (from your face?!) while you sleep. That is, if you can sleep in something that looks like the brainchild of Hannibal Lecter and a Mary Kay salesman.

You’ve seen the workout program ads: in between shots of glistening, contracting abdominals and hyper smiling people who only sweat in socially acceptable places (your amped up cleavage if you are a woman, your shaved pecs if you are a man) comes The Promise. What, you ask, can a DVD workout/exercise book/smiling B-list celeb promise me when it comes to cardio other than a perfect body, chiclet teeth and a spray tan so authentic that real sunshine is jealous? Why, the promise of an amazing ultra-high superbad caloric burn of course!

I was reminded of this the other day as the Gym Buddies and I were sweating away on the elliptical machines (not our go-to workout but they’re easy to talk on so sometimes we end up there) and one of those ubiquitous exercise program infomercials came on. While we were giggling about watching people on TV exercise while actually exercising, large letters flashed up on the screen. “BURN up to 1,000 CALORIES AN HOUR!” flashed over all those heaving chests – the “up to” in conveniently small type of course.

This infomercial – may Billy Mays rest in peace – is not unique. All fitness programs, televised and otherwise, seem to make some kind of caloric promise. Not to mention the charts in every fitness mag and diet book showing you how many calories everything from Zumba to sex burns. But how accurate are these claims? And does it even matter how many calories your workout burns?

Q: Can You Really Burn 1,000 Calories An Hour?

Anecdotal evidence first: According to my overly generous heart rate monitor of which I was once so attached to that I would turn around and go home to get the chest strap if I accidentally forgot it despite the fact that being small chested meant that it looked as if I had a 3rd nipple, I have burned over 1,000 calories in a single workout. The scene was “Holiday Turbokick” a special brand of torture that Turbo Jennie likes to put us through on occasions like the day before Easter, where we do 8 “turbos” (a high-intensity interval lasting between 30 seconds and 2 minutes) interspersed with 4 finales or some such craziness. By the end I am turbo-ing in a puddle of my own filth and can wring out my top like a Shamwow. It’s enough to make a girl puke up her turkey before she even eats it, is what I’m saying. But by the time we hit cool down, I had indeed burned just over 1,000 calories.

So it would seem possible – although unlikely (who wants to work out so hard you vomit every day?) – to attain that magic number. Except for two problems. 1) My heart rate monitor wasn’t terribly accurate. While I trusted its ability to read my actual beats per minute, its calorie burn function was apparently calculated based off a 6’6″ male Russian ice swimmer. To prove this, I switched heart rate monitors with Gym Buddy Allison, who wears a different brand, and racked up 200-400 less calories per hour than my watch gave me.

2) Even the venerable Polar or Garmin can’t really tell you your caloric burn as metabolism is so individual as to render any mathematical formula at least slightly inaccurate. The research in this area is more prolific than one might think. Companies that make a living off of guaranteeing a good workout have invested a lot of energy into trying to figure out what number of calories people can expect to expend using their machines or programs. What they have discovered however is that while they can predict how many calories an individual, say Michael Phelps, is burning, those results are very difficult to generalize. In addition to individual metabolisms there are simply too many other variables. Therefore, the honest companies will give you a range of calories. The disingenuous ones will use that sneaky little phrase “up to” and then give you a Michael Phelpsian number just to make you feel good.

3) Don’t even get me started on how inaccurate the calorie-burn calculators on the cardio machines are.

Q: Does it Matter How Many Calories You Burn?

Every fitness expert will tell you that weight loss, gain or maintenance comes down to simple math. It’s all about the calories you take in through food in relation to those you expend through daily life and exercise. This over simplified heuristic often leads people to think things like, “If the treadmill says I burned 250 calories, then that means I can eat a 200 calorie muffin and still come out losing!” This, in turn, has made calorie burn the gold standard in assessing a fitness program’s worth.

But dig a little deeper and you will realize that not only is calorie burn not the best indicator of a workout’s power, it actually distracts you from other benefits of exercise. For instance, weight lifting typically doesn’t burn comparatively as many calories as cardio for the same amount of time and yet it has many advantages like increased strength, muscle mass and overall functionality. Similarly, HIIT (high intensity interval training) burns a smaller amount of calories during the actual workout but causes a much greater spike in HGH (human growth hormone) than twice the amount of traditional medium-intensity cardio. Lastly, cardio exercise is good for many things besides just burning off last night’s dessert – like increasing your oxygen utilization, building endurance and even improving your mood.

Q: Is It Even A Good Thing To Burn 1,000 Calories An Hour?

Confession: Back in our heart-rate monitor days, Gym Buddy Allison and I were so fixated on burning a certain number of calories per workout that if we hadn’t met our quota, we’d literally do jumping jacks in place while waiting to pick up our kids until our monitors showed the “magic” number. Ignoring for a moment how dumb we looked doing that (and the fact that I was a chronic over-exerciser and very sick at that point), one must ask if it is even a worthwhile fitness goal to strive to burn a particular high number of calories. To get that kind of calorie burn, we would have to push very hard in a high intensity type of cardio. Much has been said – and ignored – about the dangers of too much aerobic exercise in the highest heart rate zones. It elevates the stress hormone cortisol, causes systemic inflammation, necesitates longer recovery and increases your risk of injury, just to give you the short version.

In addition, an often overlooked fact by dieters and diet purveyors alike is that the more you exercise, the hungrier you get. From my personal experience the more calories I burn, the more my body wants to replace them – and fast. What’s the quickest source of glycogen for our depleted muscular system? Sugar. I have found that after a long training run, it’s almost impossible for me to stay away from the Swedish Fish and other simple carbs for the rest of the day. However, when I strength train and/or keep my training volume low my sugar cravings diminish significantly (unless I’m PMSing but that’s a different story entirely). Research backs me up by showing that dieters who create a calorie deficit purely from exercise don’t lose weight – because their bodies eat to adjust. So, what’s the point in burning (up to) 1,000 calories if my body is immediately going to want to replace (at least) 1,000 calories with whatever food is easiest for me to scarf down?

Q: Do You Need a Heart Rate Monitor?

Most people I know that have a heart rate monitor were talked into getting one either by their personal trainer or a gym promotion. (Side note: Most people I know that have a heart monitor say programming the dang thing is on par with reading the tax code… in Hungarian.) Considering they’re pricey little pieces of equipment, you need to consider it’s utility before you buy. There are two main reasons to use one:

The first is “zone training” with the theory being that since you burn a higher proportion of carbs to fat at higher intensities of exercise then having preset zones will help you maximize your fat burning by keeping your heart rate from getting too high (burning straight sugar) or staying too low (burning fat but at a very slow rate). Different types of workouts are designed to take you through various zones and it can be hard to know which zone you’re in if you don’t have a monitor.

The second reason is usually calorie tracking. The watch provides a more reliable and customizable number than guessing from a website.

Okay, there is a third reason. You just like the way it looks! It makes some people feel hardcore or show that they’re “serious” about their workouts. Or they just really like the third-nipple look.

So do you need one to get a good workout? No. Are they sometimes useful to have? Yes.

Q: What do I do? 

Honestly, calorie burn doesn’t matter much to me anymore.  I haven’t worn a heart rate monitor in over two years and don’t miss it a bit. My main measure these days of a good workout is the fun measure. Granted, I’ve been exercising long enough to know what it feels like for me to be at “maximal effort” or “90% of my max heart rate” or even what my aerobic threshold (AT) feels like. I can see how wearing a monitor could help someone new to fitness learn to recognize how hard to push yourself (hint: it’s always harder than you think). But for me it ended up just being one more number for me to obsess over so just like I no longer count calories, weigh myself, or even measure my body fat percentage, I also don’t worry about my calorie burn. Call it intuitive exercising, if you will.

All of which is not to say that exercise – even an occasional session of long, intense cardio – shouldn’t be done. Ask any triathlete, marathon runner or Iron(wo)man if their race was worth it and most of them will give you an enthusiastic yes. But it isn’t because they burned 3,000 calories, it’s because they were having fun and it gave them a sense of accomplishment. Does it mean that I don’t get a great workout from Holiday Turbokick if I don’t burn quadruple-digit calories? No! I’m still increasing my endurance and having a lot of fun to boot. I’m not even saying that you shouldn’t measure your calories burned – you may find it motivating, educational or just entertaining. My long-winded point: When we are evaluating the merit of a particular fitness program, there are a lot of better factors to consider than supposed maximum calorie burn.

Do you have a favorite fitness infomercial? Anyone else ever been obsessed with burning a certain number of calories during your workout? Do you wear a heart rate monitor?

{ 42 comments… read them below or add one }

Kay May 8, 2013 at 1:06 am

The only time I’ve been really obsessed with calories is when I was very, very sick. I wasn’t working out (didn’t have an ounce of energy), but I wasn’t eating–so I’d calculate my RMR to see how many calories I could ingest while maintaining a certain daily calorie deficit.

Now I work out (mostly yoga and some cardio) and eat what I want without numbers–I don’t count calories and I don’t own a scale.


Charlotte May 8, 2013 at 2:30 pm

Sounds like we ended up in about the same place – I shouldn’t be but I’m still surprised at how many of us there are that made the same journey, lol!


Laura May 8, 2013 at 5:05 am

Tony Little infomercials in the 90s was my favourite. I bought his tapes and faithfully used them while listening to his hyper yelling orders. Phew….glad they got lost.

Another factor about calories burned, during certain times of the month women burn more calories naturally than other times. That is why we often have cravings.

Also, burning a lot of calories is hard on the body. When I was hyperthyroid, I could eat half the house and still lose weight. Sounds ideal but I was miserable. I felt achy and shaky and irritable and hot and always had a fever and I didn’t even enjoy the excess eating.

I figure it is the same thing with burning a lot of calories from a workout. It isn’t that fun to eat while starving. You just eat to feel better.

Exercise for health, fun and improved stamina is the way to go in my opinion. Rest when weary and move when restless.


Charlotte May 8, 2013 at 3:02 pm

I think this: “I figure it is the same thing with burning a lot of calories from a workout. It isn’t that fun to eat while starving. You just eat to feel better.” is an excellent point. And good point about the time of the month issue! I’m glad you got your hyperthyroid under control and are feeling better?


Alexa May 8, 2013 at 5:27 am

I used to use my heart rate monitor religiously, but its battery died earlier this year and I haven’t bothered to replace it. I’ve been doing Jillian Michaels Ripped in 30 and Body Revolution DVDs which emphasize strength training. When the HR monitor still worked I remember being disappointed in the lower calorie burn. But I’ve lost more weight and been much happier with my body tone since doing these particular DVDs. So just in the last few months I’ve come to agree with you. It really doesn’t matter what the calorie burn is…what works for me is strength training.


Charlotte May 8, 2013 at 3:04 pm

So true about the power of building muscle! So glad you have found what works for you!! Have you tried her 30-day shred?


Alexa May 8, 2013 at 6:46 pm

I have it, but I found it too repetitive- which is kind of silly considering Ripped in 30 follows the same formula. I’m also a “Firm-Believer” and I love my Firm work outs. By the way I love your blog and gave your book to a few girlfriends.


Naomi/Dragonmamma May 8, 2013 at 5:36 am

Never ever used a heart rate monitor. Using one would probably scare me to slow down, since I’m pretty sure I tend to exercise in the Heart Attack Zone.


Charlotte May 8, 2013 at 3:11 pm

You and I must workout together someday. Must.


Briony May 8, 2013 at 5:48 am

I try to avoid counting the calories I burn from exercise.I’ve had an eating disorder in the past and was lucky in that working out was never a part of that (although I would walk for hours every day) but I do find calorie counts on cardio machines really quite triggering (I know this is completely illogical). I always set the machine to show me mileage/speed instead if I can. I hate the idea of placing importance on calorie burn- it seems too much like punishing yourself for enjoying/eating food to me, and no-one should feel they have to do that.

This is not really related to the main topic of the post, but I actually find that weight lifting gives me a huge appetite! I always notice an increase in my hunger levels when I increase my exercise, but with weight lifting it seems to be much more pronounced then cardio. I’m hungry pretty much every hour, and not just ‘handful of almonds’ hungry, either. I would be interested in hearing if anyone else gets this, because it seems to counter to the current idea that weights are better because you don’t end up eating so much junk.


Charlotte May 8, 2013 at 3:14 pm

I don’t think that’s illogical at all! I put my towel over the readout so that I don’t look at them either! And so interesting about weight lifting making you hungrier. I guess if you are making new muscle you need lots of fuel to do it!


Matt May 8, 2013 at 11:34 pm

I too have found this to be the case. I used to lift in the morning some years back and I would get slammed with hunger pains like crazy shortly afterward.
I’ve found fruit to be good for that sort of thing, especialy apples for the fiber.
Over all though I’ve come to make peace with hunger. Losing weight is a lot easier when we can view it at something to tolerate within certain levels.


Maggie May 8, 2013 at 8:44 am

Even though they’re rife with swearwords, I love the Jaboody Dubs versions of Billy Mays commericals. Not to be watched with kids around or when you’re in public. You’ll laugh way, way too hard.

I used to calorie count for health reasons before I learned from multiple sources that it was essentially bullsquat. Like you said: it’s difficult to measure and not all calories are created equal. The best thing for me is to eat whole foods and really listen to my body. The vegan diet works for me.

And you’re right about the marathon. Just ran my first less than two weeks ago. One friend said, “I wonder how much weight you lost in that time!” I hadn’t even been thinking about it. Just. “Holy guacamole, I just RAN A MARATHON.”


Charlotte May 8, 2013 at 3:17 pm

Oooh I think I just found what I’m doing tonight after the kids go to bed! Haha thanks for the tip!


Amanda May 8, 2013 at 8:50 am

I use a heart rate monitor but just to monitor my heart rate…I know novel concept. I run a lot so I use the heart rate to monitor my exertion level and to make sure I’m really running easy when I’m supposed to. My watch does calculate calories but I don’t really look at them because I’m pretty sure they’re inaccurate…I refuse to believe I burned less than 400 calories for an 8 mile run. I also find that looking at that type of information starts making me obsessive so I just don’t and enjoy that I ran 8 miles instead of obsessing that I burned the correct amount of calories


Jenny C. May 8, 2013 at 9:15 am

Pandora keeps showing these commercials for Under Armor workout clothing, but it starts like a fake infomercial for Fit Fancy clothing, which is non-functional workout clothing. They always show people unable to drink their martini while on the elliptical and such. Then it cuts to the “real person” at brunch saying “in Fit Fancy, I look like I got up and ran a 10k this morning… but don’t tell my liver that!” as she downs another drink.

I know that it’s a fake commercial intro for a real commercial, but Fit Fancy is still my favorite fitness infomercial.


Charlotte May 8, 2013 at 3:22 pm

Oooh I must go find that commercial now!!


quix May 8, 2013 at 9:39 am

I heart rate train but not for calorie count – just to make sure I’m going the right intensity for the day. I’ve gotten better at guessing, but in January, what I would have called an “easy run” was actually a moderately hard run, I just wasn’t used to going easy enough!

I also have found that calorie count in workouts become less and less useful over the years. (I used to do just about the same thing – hopping in place while the dance dance revolution songs loaded so I could make sure and hit x-calories per session) As a triathlete, I try to train my body to be more efficient at running, biking, and swimming, so I can get through 7 hours of racing without stopping for pancakes at i-hop in the middle of it. So, even when I’m training 12 hours a week, and even though my APPETITE disagrees, I only really need a few hundred calories a day more on average even though every calorie calculator says I should probably be eating a lot more. I’ve tested this by slowly tweaking calorie counts and figuring out at what level I maintain and when I start to actually lose a little weight.


Charlotte May 8, 2013 at 3:27 pm

I love that you are so into tweaking your diet/routine! You are a kindred experimenter;)


Amanda O May 8, 2013 at 10:36 am

I totally hear you with this post! (And I love your concept of intuitive exercising) When my ED was at its worst I would exercise to my “magic number” of calories burned (and each day try to do more as a bonus, ugly cycle). I’ve found that with relaxing about it (and food/life in general) I actually enjoy my workouts (life) more and as a result I am much happier. I now appreciate things like yoga (previously considered a “waste of calorie burning time”) for all the myriad of benefits outside the narrow view of the number burned. Thank you for narrating your experience with this as I imagine it’s something a lot of women (and maybe men too?) struggle with.


Charlotte May 8, 2013 at 3:29 pm

This: “I’ve found that with relaxing about it (and food/life in general) I actually enjoy my workouts (life) more and as a result I am much happier. I now appreciate things like yoga (previously considered a “waste of calorie burning time”) for all the myriad of benefits outside the narrow view of the number burned.” I just want to scream YESSSSS!!! You said this perfectly, Amanda!


Abby May 8, 2013 at 10:53 am

While I’ve never used a heart-rate monitor I used to be obsessed with the calorie counts on the cardio machines. Then in recovery I couldn’t look at them for the longest time because it’d be too triggering. These days I always want to see but more as a fun fact than anything else. I can tell you in my 5 minute pre-weights warm-up yesterday I burned 36 calories, lol, and the last time I did cardio on one I burned around 300. (According to whatever math it uses…) Any workouts prior to that I have no idea and I don’t really care. And that’s an amazing thing for me.


Charlotte May 8, 2013 at 3:30 pm

This comment made me smile and smile:) Congratulations, my friend! It’s these little victories that are so beautiful!


Kim May 8, 2013 at 11:02 am

I don’t wear a heart rate monitor and I gave up on the calories burned a long time ago. I used to be obsessive about programming my age, gender, weight….into machines before I used them so I could see how many calories I was using. I finally realized that all of that didn’t matter because the next person could have totally different info and burn the exact some number of calories. Now, distance and time I still am very obsessive!!!


Charlotte May 8, 2013 at 3:33 pm

Haha, us numbers/competitive types have to measure something! These days I get obsessive about my weights and reps, lol.


Kara May 8, 2013 at 11:38 am

I use a heart rate monitor for my running and that is it. Mainly it is so that if my training schedule has me running negative splits or a certain speed workout I can access the info. and do the workout. When I get home and upload it to my computer I don’t get too hung up on calories I mainly am looking at how my heart performed during the 400m repeats or the hill climbs, Was I off the charts; is it starting to feel more “comfortable”? Etc.


Charlotte May 8, 2013 at 3:36 pm

That’s a good useful “use” for an HRM! It is definitely a tool and it has a place in training!


Jess May 8, 2013 at 2:52 pm

Never used a heart rate monitor and I don’t intend to. As far as calories go, I don’t really think it’s the most important metric to look at for weight loss.


Katie May 8, 2013 at 6:23 pm

As usual, you’ve taken the thoughts out of my head and written them much better than I could ever hope to. Yes, I’ve overexercised. Yes, I once own and religiously wore a HRM (during my P90X and Insanity days, of course….curse on you, Tony!!). No I haven’t worn it in years. In fact, I sold that bad boy on Craigslist for almost full value!

I’ve bene exercising for so long, that I really don’t need it or care about the numbers anymore. I strive for 60ish minutes a day, and try to make at least 3 of those be “kind of” intense-ish. (Note all the caveats there, they are important to my sanity.) The others can be and usually are walking, light biking, yoga, whathaveyou. You know, things that don’t really burn an appreciable number of calories but are still hella good for your body and soul. I’m working more on my soul these days than my body. Except, no. I’m working on my BOOTY and soul. Hehe.


Jess May 8, 2013 at 10:29 pm

I used to be a little (or a lot) like you and your work out buddy were, and obsess over the numbers. I would hvave totally done jumping jacks until I hit that number. I now realise that just hitting that number doesn’t really matter (and you’re right probably inaccurate). Great post!


Matt May 8, 2013 at 11:31 pm

Great article Charlotte! My stance has long been that while we understand that fat management is about calorie balance, it’s knowing and understanding that calorie balance that’s so darn hard. To me it’s like plate techtonics. We know it happens, and we can measure the effects of it in earth quakes, tsunamis and mountain ranges. But using it to know what’s happening now and what’s going to happen in the future is more educated guessing than anything.

That’s why I don’t even both counting the darn things. I just look and pay attention to my body if I’m eating too much.

Also, as a rule I don’t count calories burned during a workout to be of much significance unless I’ve been doing continuous activity for at least 2-3 hours. Just my thoughts……


Katie May 9, 2013 at 5:45 am

I don’t have a heart rate monitor, never have, but I confess to paying attention to the cardio “calories burned” display. I always adjust it to my weight, and so the total at the end of my workout is depressingly low. These days I don’t care about the calories anymore but I’m still addicted to working out for a certain amount of time every day.


Leth May 9, 2013 at 10:13 am

I’ve definitely found out about the exercise vs. hunger thing. I’ve been on the injured list for four months, and I’ve lost more than 10 pounds. I’m sure some of that is muscle, but I feel like the majority of it is because I’m not as hungry anymore. I can eat a lunch of a medium bowl of meat and veggies and not worry about my stomach eating itself mid-afternoon like it did when I was doing Crossfit regularly. For me, it seems that exercise is really about fitness and health, but weight management really comes from diet and moderation.


Tamara May 9, 2013 at 10:18 am

I stopped paying much attention to calorie burn of workouts a while ago. This recent article only reinforced that I was on to something:


Alyssa (azusmom) May 9, 2013 at 1:28 pm

For a long time I was obsessed with the P90X infomercial. Even after I’d sold my DVDs. I kept wondering if maybe I’d done it “wrong,” since I didn’t get the same results as everyone in the infomercial. Then I’d remind myself that the reason I didn’t get those results was because I kept getting injured.
I also tried “Insanity.” Ditto. I just don’t think the human body is meant to work out at that intensity (“reverse” intervals, so you’re working out at a high intensity for longer periods and recovering for shorter ones) for that amount of time (nearly an hour) 6 days a week! Sure, you’ll probably lose weight, but at what cost?
And, yes, I used to obsess over calories burned, and I used to wear a heart rate monitor. Not anymore. And I try to avoid workouts which emphasize caloric burn and “Just think how great you’re gonna look in that tank top!” talk. yes, I want to look good. Yes, I want to lose weight. But I want to do it without hurting myself, and I want to actually be fit, strong, and healthy. Not skinny.


Sue May 9, 2013 at 5:42 pm

Do calories matter at all? It it true if we eat more calories than our bodies need we will gain weight? I am trying to increase more fat in my diet but am worried that l will gains weight. I have been eating less and am very tired and feel unwell, l just need to find a way to free myself from dieting, and l now that if l eat more l will feel better, but l need to over come my body image issues. You would think at at 42 l would have achieved my peace with food. I don’t know how to trust my body. I went to put on my jeans the other day and they were all too tight, so l went on this mad diet which made me feel unwell. Why can’t l just throw those jeans away and buy a new pair? Why? I hate running and l hate dieting, l just want to be free. But easier said than done. Your lucky Charlotte that you are able to wart when hungry and still fit into your jeans, I tried that and l gained, so l guess l just need to except that.


Roy Montgomery May 10, 2013 at 6:00 am

For most people yes it does. They want to burn off as many calories as possible if they are out for a run, down the gym or exercising at home.


Bek @ Crave May 10, 2013 at 8:06 am

I use to and like you it just was another number I obsessed about. Then I stopped and now I just wore the watch without the strap ha. It was good to keep track of which mixes were more or less challenging when I taught group fitness though


Katy @ byebyedoc May 10, 2013 at 3:38 pm

Don’t watch calories or use heart monitor. Those make the process of exercising very mechanical and take away the enjoyment.
I do have a close watch on my weight though.


eyanmorgan May 13, 2013 at 7:09 am

Hello katy.. I agree with you. While doing physical workouts no need to count no of calories burn. Sometimes we may do long time and sometimes may not due to busy schedule. Rather than counting for calories burn, do physical exercises as much as you can, you will reach your weight loss goal in a healthy and effective way.


Happier Heather May 20, 2013 at 2:09 pm

I’ll admit it. I used to wear an HRM and do the jumping jacks at the end of a workout to get to my calorie goal, too. I finally realized that I can’t out-exercise eating too much junk food, so I’ve gone back to focusing on eating in a reasonable calorie range and exercising for its other benefits.

I’ll also admit that I LOVE watching exercise program infomercials. I get sucked in every time.


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