Math question about earning extra calories by exercise

Sorova

Let me start by saying that I *do* eat back my exercise calories and I know from experience it's a good idea. I am absolutely against the practice of having massive deficits (to me any deficit over 1000 is bad) and I aim for a calorie deficit of 500-800 per day once all exercise and food is factored in.

My question is purely about the math and whether the website is being precise about how many calories we're really earning through exercise. A simple example for illustration:

Let's say it takes me 2400 calories per day to maintain my current weight. I'm not talking about BMR here, I'm talking about the calories I burn in my normal daily activities, with no exercise factored in. That means I burn an average of 100 calories per hour just walking around, making tea, buying hats, whatever.

Now, add in exercise: let's say I spend 1 hour per day working out, and in that hour, I burn 400 calories. From what I've seen so far on the website, the website will tell me to eat an extra 400 calories that day.

But that doesn't make sense to me mathematically, because it assumes that I burned all the calories I would normally burn, plus an extra 400. But in actuality, for that hour I spent working out, I would have burned 100 if I wasn't working out. So I have burned 300 extra, not 400.

For this reason I tend to eat back my exercise calories except for 75-100. I'm new to the website, and I was just wondering if anyone else had noticed this and whether it had been discussed before.

RonSwanson66

Any numbers given to energy expenditure due to are an estimate, and a poor one at that.

In fact, the whole idea of tracking your activity and "eating your exercise calories" is fundamentally flawed. Not only does it overcomplicate the matter, but you're adding error onto error. It's no wonder we have so many people here who don't understand why they're doing what MFP says they're supposed to and still end up spinning their wheels.

You would be much better off factoring your exercise into your daily activity, and basing your intake on that.

Put simply, to find maintenance level, multiply your bodyweight by 14-16 (a little lower if you're sedentary, higher if you're especially active). Then subtract your deficit.

So a 200 lb man who exercises regularly would have:

Maintenance: 200 x 15 = 3000 calories. To lose 1lb/week he would eat 2500.

Track your results and adjust as necessary. If you aren't losing, shave some calories off.

ATT949

Your perspective is correct. To be "accurate" you need to net out the pro rata portion of your daily calorie expenditure.

There are many, many inaccuracies in tracking calories - we weigh food incorrectly, we forget food, we use the wrong food when we make diary entries, our BMR's are inaccurate (mine is about 300 cals lower than the MFP estimate), our exercise calories can be laughably inaccurate, etc., etc.

When I was losing wieght, I had a large enough deficit that all of the inaccuracies didn't matter and, from every measure, it worked.

http://cbeinfo.net/weight.htm

carrie_eggo

Great post....It annoys me to see all of the "why am I not losing" / "eat your exercise calories" threads, and yet no one seems to mention inaccuracies and human error.

BobbyClerici

I say NO!

So, knowing this, I tweaked it and played around with the numbers to find that sweet spot on the spectrum representing daily maintenance: 2200 - no exercise.

I placed my settings for "VERY ACTIVE" and calculate for 90 minuted of daily cardio but not for my 30 minutes of daily resistance.

At the end of it all, I lose 1 lb each week, and I eat around 3000 calories each day.

It works!

DesertSunsetRain

Someone else posted a similar question awhile ago and I am still not understanding why you don't ADD it together.

You would have normally burned 100 if you didn't work out, but you burned 400 EXTRA calories on top of what you normally burn. So isn't that 500 for the hour?

agthorn

You would be much better off factoring your exercise into your daily activity, and basing your intake on that.

But that takes all the fun out of biking an extra 25 miles so I can eat an entire wood-fired pizza later that night.

lin7604

wow am i ever confused.....

jaabee11

huh?

klewis81

I completely get what you are saying. There is some error in however you are tracking food in or energy out. My suggestion would be to not eat back all of your exercise calories. I try to have 100-200 calories left over by the end of the day. I am only on a 1 lb/week loss so there is no way I am going to hit that dreaded "starvation mode".

The bottom line is: if it is working, keep doing it! If you aren't losing weight, change up your method!

Coyla

Not sure if I agree with the idea of eating back exercise calories, either. I do like the idea of factoring in your activity level, however. Hmmmm...

There are several problems with exercise calories. First, MFP estimates the calories burned far too high. I have a heart rate monitor, and it calculates about a 3rd of what MFP calculates.

Another problem is the after-burn effect. After a morning of great cardio, my heart rate is elevated for several hours after, so I burn more calories for the entire day. But those extra calories are never factored in.

And then there's strength-training. When you tear your muscles apart via strength-training, they need energy (calories) to repair. And there's no way of calculating how many calories extra they need or how long it takes. Those calories are never factored.

Anyway, it's always a guessing game. However, using MFP as a guide does have its benefits.

Sorova

Someone else posted a similar question awhile ago and I am still not understanding why you don't ADD it together.

You would have normally burned 100 if you didn't work out, but you burned 400 EXTRA calories on top of what you normally burn. So isn't that 500 for the hour?

No, you burn 400 total that hour, not 400 extra. That's just the way exercise calories are estimated, either using a heart rate monitor or a database like on this website. Using the numbers from my example, the first 100 calories represents the things your body normally does (pumping blood, digesting food, working your brain) and the other 300 represents the extra calories from working out. And yeah, all of this is just the theory. In practice, things aren't so neat and tidy and easy to measure or predict.

Anyway, thanks for the replies everyone. You're right that focusing too hard on the numbers isn't the way to go. In practice, I know that all the numbers are approximations. MFP is a great guideline and I can always adjust from that starting point based on the results I see.

That being said, even if I am going to go by approximate numbers, I still want to use mathematically sound methods of analyzing those approximates. Mostly, I was just curious about whether the website designers had a specific reason for presenting things the way they have. My personal approach is to use a HRM when exercising for slightly more accurate numbers, and to eat back most of my exercise calories. This has worked for me before and it's comfortable for me. By no means am I here to tell anyone else how they should do it--I just wanted to know whether the website staff ever talked about it publicly before I showed up.

CannibalisticVegetarian

wow am i ever confused.....

Ditto.

linmckenna

Not to make things more complicated...but I would also be careful when calculating the number of calories you can consume a day in order to maintain weight. I just finished an introductory nutrition college course. My teacher had us calculate our EER (number of calories you can eat to maintain your weight). My number came up as 2200, but she said from her experience as a nutritionist this number is always too high. The equation was set up years ago when people were generally more active. She told me my number is more like 1800-1900, which is a pretty big difference! I have since adjusted to only eating 1500 calories a day (not the 1800 I was eating before) and I am seeing results.

Oh and on the topic, I also do not believe in eating back the calories you have worked out. What's the point of working out? I have my limit set to 1500 a day and do not pay attention to the "earned" calories from exercise.

Pebble321

Yes, this question/observation comes up pretty regularly.

While I appreciate that to be mathmatically correct you should subtract the extra cals, I don't do it.
Like several of the previous posters, I accept that every single number I use (food cals, exercise cals, BMR etc) are all estimates, and I started losing weight quickly and steadily so I didn't ever need to obsess about every single calorie.

For me the basic principles (enter your data, generate a number, eat these cals, eat more when you exercise) just works, I don't see the need to complicate it.

And for the "I don't see the point in eating your exercise cals" people - I can only assume that you don't understand the maths that the OP is talking about, and the way MFP is set up:
- MFP is designed to give you a regular, moderate calorie deficit.
- By not eating your exercise calories you are creating a larger deficit.
It's that simple! Whether that large deficit is a good thing or not is going to depend on each individual's personal situation, what works for one person isn't necessarily going to work for another.
Increasing your activity level to include exercise is just another way to do what MFP is doing. If you prefer it that way, go for it!

Sorova

In my opinion, talking about "eating back" exercise calories is a confusing way to put it because it makes people think they're canceling out their work. All that matters for weight loss (at least in theory) is creating a deficit: burning more than you eat. You can create a deficit by reducing the calories you eat, increasing the calories you burn, or with a combination of the two. The suggested deficit is 500-1000 calories per day.

Having too big of a deficit can slow your metabolism down (starvation mode). So for example, if you need 2500 calories to maintain, eating 1200 is probably not a good idea unless you have medical supervision. Similarly, if you use exercise enough in a day to burn 3000 total calories, but you only eat 1800, you may have too large a deficit.

Obviously, questions of what deficit is too large can vary from person to person. I'm just going by what I've read and what I've been told by doctors and nutritionists. Hopefully this will help some people understand where I'm coming from. I aim for a deficit of 500-800 per day, and in order to make sure I don't have a larger deficit than that, I do need to factor in exercise.

Rae6503

I don't worry about that. It works for me to not do so. You can handle it however you want and see if it works. Like everyone said there is a lot of error and really the whole calorie counting thing is just a game that motivates you to ultimately burn a little more than you eat. If you lose weight you win the game, so play by whatever rules you want.

Sorova

I don't worry about that. It works for me to not do so. You can handle it however you want and see if it works. Like everyone said there is a lot of error and really the whole calorie counting thing is just a game that motivates you to ultimately burn a little more than you eat. If you lose weight you win the game, so play by whatever rules you want.

I hear you 100%. In fact, I have found personally that once I was able to have faith in the core "be more active and eat better" approach without worrying about every calorie like an accountant, I have been less anxious and more successful. As for different approaches to exercise calories: as I said, I know everyone is different and people should do what works for them. The only reason I shared my understanding of the deficit principle is that some people didn't seem to realize what I meant.

I probably shouldn't have posted the thread, as I certainly didn't mean to stir up trouble. I was just interested in elaborating on the math behind weight loss and understanding the formula used by the site--perils of being a nerd, I suppose.

rita27ny

what about deficient of 100calories. do u think i should eat it back? i eat 1200 calries sometime 1600 when im going to workout that day. what if i burn 500calories should i eat back the 100 calories?

Rae6503

I understand completely. I'm a huge nerd when it comes to all this. I even have a awesome spreadsheet tracking everything.

ninerbuff

If weight loss was totally mathematical then stalls and plateaus wouldn't exist.

A.C.E. Certified Personal Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 28+ years and have studied kinesiology and nutrition

juliapurpletoes

ok....be smart about this! you DO need to adjust off your resting calories to get an accurate burn...that was explained to me along time ago! so if you burn 1 cal per minute sitting at your computer that don't re count it with your exercise calories...

adjust it and then you'll get accuracy...


edit for spelling....

traceracer

Honestly, I never used to count calories at all the first time I lost weight and the weight came off like crazy!! 2,3, sometimes 5 ponds a week!!! I was exersizing eveyday and eating healthy any time I felt like it!! I based my label readings on no more than 3g of fat per 100 calories. Now that Im back on the band wagon and following my calorie in/outs, I am struggling to loose a pound a week!! Starting to think that mabe I should go back to my original plan......

traceracer

Honestly, I never used to count calories at all the first time I lost weight and the weight came off like crazy!! 2,3, sometimes 5 ponds a week!!! I was exersizing eveyday and eating healthy any time I felt like it!! I based my label readings on no more than 3g of fat per 100 calories. Now that Im back on the band wagon and following my calorie in/outs, I am struggling to loose a pound a week!! Starting to think that mabe I should go back to my original plan......

I should have said anytime I have lost weight in the past....not just the first time!

Pebble321

...
I probably shouldn't have posted the thread, as I certainly didn't mean to stir up trouble. I was just interested in elaborating on the math behind weight loss and understanding the formula used by the site--perils of being a nerd, I suppose.

Don't say that, it's much more fun to throw around numbers than plain old "what is the point of exercising if I'm just going to eat them back". I love the numbers side of it, to me it makes it a bit of a game to try to get the calories balancing at the end of the day. I'm up to 325 consecutive days and I think I've only come out at 0 cals remaining once or twice - numbers make it fun!

kittenjazz

Ya, tracking your own data is ideal. For each week, you can calculate pounds lost, calories consumed, calories burned and use this to determine how much the actual pounds lost compares to the theoretical (based off net calorie deficit), then adjust as necessary

kittenjazz

But aren't those mathematical as well. Something at the cellular level, most likely slowed down metabolic rate results in plateaus. Still mathematical. It is just a dynamic mathematical model is all.

jovz10

The bottom line is: if it is working, keep doing it! If you aren't losing weight, change up your method!

totally agree!

Elleinnz

Yes - I totally agree with you - I wear a Bodymedia Fit - so know that I burn around 80 calories when I just sit on the couch....so any calorie burns I get from true exercise (not housework etc) is "overstated" by that 80 calories....

Initially I actually deducted 80 calories and hour before I logged my exercise - now I just log the full burn - but only eat back around 80% of my exercise calories

shakybabe

so if I'm 147lbs and i exercise daily so use the 15 I should be eating 2,205!!! so this is to maintain that weight? .. and 1,705 to lose 1lb a week, and 1,205 to lose 2lb a week?

but I want to lose another 18lbs and be 129lbs, someone said a theory to eat the amount of calories that matches the weight you want to be or something?

so 129 x 15 = 1,935 to maintain that weight? MFP has me at 1200?? which I was following.. however I found when I got my monthly cravings and was eating more that week.. once the water came off I'd find I had lost another 3-4lbs besides the water coming back off and get my biggest loss that week.. the other weeks at 1200 sometimes nothing.. if lucky 1-2lb.. usually 1!

kmbrooks15

This is why I invested in a Body Media armband. It tells me exactly what I've burned ALL DAY, then I put in my consumed calories, and it calculates my deficit. My numbers have been very different from what MFP was telling me since I got it, and I'm losing more consistently with it than I did without it.

I understand why people are confused about eating back their exercise calories because I didn't understand it at first either. I do now, but I also agree that MFP's calorie burn estimates can be way off, simply because it doesn't take into account how hard you were working, your body weight at the time, and many other factors. That's why a HRM or an armband to track your burn is so much more accurate.