What To Do

Categories

Social Bookmarks

Feeds

General Fitness & Nutrition: Overvew of our Calorie Calculations

Bottom of Page

1 to 8 of 8

  1.  
    • CommentAuthorkevin@mmf
    • CommentTimeAug 8th 2007
     
    kevin@mmf

    Many people have asked me how we calculate calories on this site, so I've decided to post an answer.

    We use a combination of BMI, time taken, and MET score to estimate your calories burned.

    BMI is your body mass index score and is based on your height/weight ratios. For more info: http://www.whathealth.com/bmi/formula.html

    MET (Metabolic Equivalent) is the ratio of the work metabolic rate to the resting metabolic rate. One MET is defined as 1 kcal/kg/hour and is roughly equivalent to the energy cost of sitting quietly. A MET also is defined as oxygen uptake in ml/kg/min with one MET equal to the oxygen cost of sitting quietly, equivalent to 3.5 ml/kg/min.

    Specific activities have a working MET -- ie, walking at a very slow pace (less than 2mph) for an hour will be the equivalent (ie., burn the same calories) to sitting still for two hours. The METS for this activity is 2.0

    See: http://prevention.sph.sc.edu/tools/compendium.htm

    So the final equation bringing this all together is:

    Calories Burned = (MET value) X (BMI/24) X (duration of activity in hours)

    To see this formula in action, visit our calorie calculator

    -Kevin
    Co-Founder, MapMyFitness

    • CommentAuthormberry133
    • CommentTimeAug 10th 2007
     
    mberry133

    What about elevation?

     Today I did a 37 mile ride where I went up and down 2400 ft. A week ago I did a 51 mile ride where I went up and down about 800 feet. The calories for the 51 mile ride were 50% higher than the 37 mile ride, but let me tell you that 37 miler was much, much harder.

    (Also, got to tell you I love the site!!! especially now that I am on Firefox)

    • CommentAuthorrhaebus
    • CommentTimeAug 14th 2007
     
    rhaebus
    Yes I'm also interested in how elevation goes into the calculation (if at all)
    • CommentAuthorfrosted
    • CommentTimeAug 15th 2007
     
    frosted

    What I don't understand is this:

    I go for a 3.5 mile walk every morning.  I incorrectly entered in 55 minutes and it said I burned 237 calories (or something similar).  When I corrected it to 54 minutes, it said I burned 309 calories.  Something ain't right with that.  1 minute less does not = 70 cals.  It seems that at 4 mph everything changes, and I think this is incorrect.  

     

     

    • CommentAuthorkevin@mmf
    • CommentTimeNov 1st 2007
     
    kevin@mmf

    If we look at the MET compendium, we do break down activity by speed -- ie,

    6.0 bicycling bicycling, 10-11.9 mph, leisure, slow, light effort
    8.0 bicycling bicycling, 12-13.9 mph, leisure, moderate effort
    10 bicycling bicycling, 14-15.9 mph, racing or leisure, fast, vigorous effor
    12 bicycling bicycling, 16-19 mph, racing/not drafting or >19 mph drafting, very fast,

    So the gaps you may be looking at breaks across these boundaries.  We're looking into ways to make this more incremental.

    We're also looking at changing our BMI formula and was wondering if any users have experience with these calculations in determine a more accurate estimate:
    http://blog.forret.com/2006/03/bmi-is-not-perfect/

     -Kevin

     

    • CommentAuthoraju
    • CommentTimeNov 2nd 2007
     
    aju

    These speed brackets need to be adjusted for elevation gains.  I am quite sure that while climbing a steep hill on my bike at 7 mph I'm burning far more calories than someone riding at 6.0 bicycling bicycling, 10-11.9 mph, leisure, slow, light effort. 

    Because this program does not take into account speed at particular points on a course, there isn't really a practical way of calculating speed up a grade.  However, the work done to move mass up a hill is fixed, and can be adjusted for speed using the average speed in the speed bracket as you are currently doing.  The work formula I found on the web for cycling is:

    W = F x D

    Ce = W/CFCi = Ce/Eef = EvWhere:W = work (ft-lbs or kg-m)F = Force from gravity (lbs or kg)D = distance vertically (ft or m)Ce = Calories expended at the pedalsCF = conversion factor of 3907 or 418 (for American and International Units respectively)Ci = Calories ingested = EvEef = efficiency of the human machine in converting food Calories (~25%)
  7.  
    Water_man11

    Kevin,

     Sounds like you should hire aju to write the code and explanations of cal. use and various activities!!

     

    • CommentAuthorjawa9000
    • CommentTimeApr 6th 2008
     
    jawa9000

    Any updates to the elevation change being added to the calorie calc?

     

    Thanks! 

1 to 8 of 8

  1.