The math error with eating calories back

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Francl27
Francl27 Posts: 26,371 Member
in Health and Weight Loss
So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

So... I'm guessing MFP isn't right when just adding exercise calories to your goal...
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Replies

  • nolachick
    nolachick Posts: 3,278 Member
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    interesting because I've always wondered if I should be subtracting out the calories that I would burn while stationary from calories burned during working out.
  • ldrosophila
    ldrosophila Posts: 7,512 Member
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    HMMMM interesting thought now I know there does continue to be some continued "calorie burn" post exercise especially in regards to the energy required for muscle repair and the heart rate does remain elevated for a period of time.

    I dont have a degree in exercise physiology though so I can't really argue the point.
  • lizziebeth1028
    lizziebeth1028 Posts: 3,602 Member
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    So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

    So... I'm guessing MFP isn't right when just adding exercise calories to your goal...

    None of this is going to be spot on. Just like the estimation of calorie intake isn't 100% accurate, the estimation of calories burned isn't 100% accurate, your estimated tdee isn't 100% accurate. There's a margin of error in the whole process. It's just meant to be a guideline, a starting point. If you find that eating back every last calorie burned isn't working that well then you need to adjust. One hundred years ago or so people didn't have these kind of tools to lose weight - HRM's, calorie tracking websites, pedometers, and other techy gadgets- they still lost weight. Eat less, move more, use commonsense and don't take things so literally.
  • omma_to_3
    omma_to_3 Posts: 3,265 Member
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    I would think that MFP would take that into account. I believe the calorie counts should be NET of your BMR. That said, I don't use MFP's numbers. I use my HRM and do subtract out my BMR from the numbers I get. Just last night, I ran on my treadmill. My HRM, after subtracting my BMR, said that I burned 436 calories. My average speed was just under 5 mph. When I use MFPs 5 mph jogging method, it was 442 calories I think. Pretty darn close.
  • BflSaberfan
    BflSaberfan Posts: 1,272
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    Then adjust your calorie intake to 100 calories less
  • erinsueburns
    erinsueburns Posts: 865 Member
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    It is all fuzzy math anyway. You don't really know exactly how many calories you are eating. Packaging can be off, food numbers are averages etc. You also don't know precisely how much you are burning. Not what your exact BMR is, not what your exact exercise burn is. It is all just general round numbers. And since most people don't have a BMR of 2400, the risk of error from that area is much less than from any other thing in the day.
  • cwolfman13
    cwolfman13 Posts: 41,867 Member
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    So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

    So... I'm guessing MFP isn't right when just adding exercise calories to your goal...

    I don't use the database...those are just wild estimations anyway based on other people's burns. I subtract my BMR calories from my HRM though...it's my responsibility to do so, not MFPs.
  • Riemersma4
    Riemersma4 Posts: 400 Member
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    I eat back 75% of my exercise cals. Takes carry of the problem.

    good luck!
  • MrsBach
    MrsBach Posts: 34 Member
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    I wear a BodyMedia Link all day to track my burn and sync it a few times each day.
  • KeithAngilly
    KeithAngilly Posts: 575 Member
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    So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

    So... I'm guessing MFP isn't right when just adding exercise calories to your goal...

    None of this is going to be spot on. Just like the estimation of calorie intake isn't 100% accurate, the estimation of calories burned isn't 100% accurate, your estimated tdee isn't 100% accurate. There's a margin of error in the whole process. It's just meant to be a guideline, a starting point. If you find that eating back every last calorie burned isn't working that well then you need to adjust. One hundred years ago or so people didn't have these kind of tools to lose weight - HRM's, calorie tracking websites, pedometers, and other techy gadgets- they still lost weight. Eat less, move more, use commonsense and don't take things so literally.

    Well put. This should be required reading before granting someone an account here! This process doesn't have to be stressful.
  • omma_to_3
    omma_to_3 Posts: 3,265 Member
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    So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

    So... I'm guessing MFP isn't right when just adding exercise calories to your goal...

    I don't use the database...those are just wild estimations anyway based on other people's burns. I subtract my BMR calories from my HRM though...it's my responsibility to do so, not MFPs.

    The exercise is not user entered values. We cannot add exercises to the database so it's not actually 'other people's burns'. It's generic things set up by MFP and they do appear to take your body weight into account. When I was less fit, walking and running was actually greatly underestimating my calorie burn compared to my HRM. Now that I'm more fit, it's usually a slight overestimate if I were to use MFPs numbers.
  • Sweets1954
    Sweets1954 Posts: 506 Member
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    I don't see the point fo "eating back" the calories you burned doing exercise. Isn't the point to lose weight? and from what I understand the way to lose weight is to decrease the input and increase the output. If you are "eating back" the calories burned aren't you defeating the purpose of exercising?
  • choirmast
    choirmast Posts: 7 Member
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    The proof will be in the weight loss.

    I do eat back many of the calories I "earn" from exercising. I am on a 1700 calorie a day net budget targetted at a 2 pound per week loss. If I eat a 300 calorie breakfast and a 300 calorie lunch, that would leave me 1100 calories for dinner. I like to have some wine with dinner. I know that the only way I can do that and still have a satisfying dinner is to earn some extra calories during the day. That really gives me motivation to get to the gym or walk the dog.

    But the proof is that I have been losing pretty consistenly the 2 pounds a week I am aiming for I have been pretty much spot on in my net calories each day, Often I have a few left over and only occassionally do I go over.

    So how is it working for you? If you are eating those extra calories and still meeting your targetted weight loss, the system is working for you.
  • AngeVanB
    AngeVanB Posts: 1 Member
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    Think of this as a guide, not an exact science. Before I began on MFP, I ate too little and my body was acting as if I were starving; it held on to every calorie I ate and I put weight on. Now I'm losing at a healthy rate and making this a part of my lifestyle! I have some friends who are on here, too, and we've talked about just what you bring up. Here's my answer to them and I hope it makes sense:

    When you start MFP, you get the number of calories you have to eat in a day based on how much you want to lose, in how much time, your normal activity level without exercise, your age, etc. If you're trying to lose weight, that would most likely be under the 2,000 and some calories you burn by "doing nothing" so you CAN lose weight without exercising. However, that is not the healthiest choice because moving your body has benefits beyond weightloss. ANYWAY, if you exercise, you should eat those calories back to get your NET intake back to your assigned daily calorie intake. So I get 1,200 calories to eat per day. If I don't exercise, I only eat 1,200 per day. If I do exercise and burn 500 calories, for example, I eat 500 extra calories to equal 1,700 calories eaten that day. My NET intake is still 1,200 (1,700 calories eaten - 500 calories burned off through exercise = 1,200 calories). If you NET too few calories, so below 1,200 a day for most people, over time, your body will think it's starving and hold on to every calorie you take in -- and you could gain weight by eating too little! It happened to me. Now, as long as I NET 1,200 calories per day, I'm losing, at a healthy and sustainable rate. When I exercise, I get to eat more, or have a glass of wine -- now that's cool! Seems counterintuative, yes, but it's working. And remember, think of it as a guide. If you are over or under your calories by 5, 10, 20, it's OK; just don't go past 50-100 more or less on a regular basis. :wink:
  • omma_to_3
    omma_to_3 Posts: 3,265 Member
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    I don't see the point fo "eating back" the calories you burned doing exercise. Isn't the point to lose weight? and from what I understand the way to lose weight is to decrease the input and increase the output. If you are "eating back" the calories burned aren't you defeating the purpose of exercising?

    You need a calorie deficit to lose weight. If you are following MFPs model, they have already created an appropriate deficit for you in your daily calorie goal. If you work out, your deficit gets larger. Not only is that hard to sustain in the longer term, too big of a deficit can be unhealthy.

    I'm currently set up with about 400 calorie deficit per day, and I lose on average, about .75 lbs. a week. I'm at the end of my journey, so slower losses are expected. When I work out, I burn anywhere from 400 to 1200 calories depending on the day (the 1200 would be a 2.5 hour run). That is just too big of a deficit and there's NO WAY I would be able to work out eating that little. NONE.
  • S_Arr_Uh
    S_Arr_Uh Posts: 77 Member
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    I don't see the point fo "eating back" the calories you burned doing exercise. Isn't the point to lose weight? and from what I understand the way to lose weight is to decrease the input and increase the output. If you are "eating back" the calories burned aren't you defeating the purpose of exercising?

    No, because you still have your original deficit to lose the weight. Sure, you could lose faster without eating them back, but your body needs some energy to make up for the hard work it did during the workout. Not to mention that you continue to burn at a faster rate than normal post-exercise so you"ll just be creating huge deficits which could result in what everyone on here fears the most: disrupting your metabolism, plateauing etc.
  • ColleenRoss50
    ColleenRoss50 Posts: 199 Member
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    So, let's say you normally burn 2400 calories. That's 100 calories an hour doing nothing, right? So you exercise for one hour for 400 calories... and you eat back those 400 calories. You ate 100 extra calories, that you would have burned anyway even if you were not exercising.

    So... I'm guessing MFP isn't right when just adding exercise calories to your goal...

    None of this is going to be spot on. Just like the estimation of calorie intake isn't 100% accurate, the estimation of calories burned isn't 100% accurate, your estimated tdee isn't 100% accurate. There's a margin of error in the whole process. It's just meant to be a guideline, a starting point. If you find that eating back every last calorie burned isn't working that well then you need to adjust. One hundred years ago or so people didn't have these kind of tools to lose weight - HRM's, calorie tracking websites, pedometers, and other techy gadgets- they still lost weight. Eat less, move more, use commonsense and don't take things so literally.

    Very well said! :)
  • wikitbikit
    wikitbikit Posts: 518 Member
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    None of this is going to be spot on. Just like the estimation of calorie intake isn't 100% accurate, the estimation of calories burned isn't 100% accurate, your estimated tdee isn't 100% accurate. There's a margin of error in the whole process. It's just meant to be a guideline, a starting point. If you find that eating back every last calorie burned isn't working that well then you need to adjust. One hundred years ago or so people didn't have these kind of tools to lose weight - HRM's, calorie tracking websites, pedometers, and other techy gadgets- they still lost weight. Eat less, move more, use commonsense and don't take things so literally.
    :love: :love: :love: :love: :love:

    I just want to read this over and over and over again all day all day all day. And then read it again. AND THEN MAKE OTHER PEOPLE READ IT GRR RAWR! And then read it over and over and over all day all day all day.

    It's great to think about all this stuff because it means we're engaged in it, but that is really it, bottom line.
  • llkilgore
    llkilgore Posts: 1,169 Member
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    I would think that MFP would take that into account.

    I don't think so. MFP didn't create their exercise database, at least not the core of it. It's been around for a while and I've seen older implementations of it that stated up front that the estimated burns reported were gross, not net. That said, it probably doesn't make much of a difference unless you log a lot of minutes of a relatively low intensity form of exercise, like walking at a casual pace.
  • Francl27
    Francl27 Posts: 26,371 Member
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    Ok I know it's all approximate. It's still a pretty big difference though.

    This morning I did a 42 minutes 278 calories workout (some cardio, some strength). You say it's not a big difference, but it is. MFP added 278 calories to my day. But I would probably have burned 80 in the same time sitting at my desk. That's 30% of my workout!

    Imagine that someone takes a walk for an hour, and is all excited to burn 200 calories, enters that and eats them back. They really only burned an extra 100 calories in that walk. MFP gives us a deficit, based on our daily total calorie spending. By eating 100 extra calories, that person decreased the deficit by 400. For a 2.5 hour walk, the daily deficit would be reduced by a half!

    MFP didn't create the database, but they created the program that adds all your exercise calories to your daily calories. IMO they should have accounted for our TDEE in there. IMO letting people believe that it's ok to eat all your calories back and still lose whatever your goal is, is inaccurate.

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