Based on BMR (basal metabolic rate), fundamental biophysics and open activity database, we provide a Calorie estimation approach that can take into account the human age, gender, weight, height, step count and duration.

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Calorie Estimation on
Wearables
jAMES Wang
June 2015

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Snapshot
• Based on BMR (basal metabolic rate), fundamental biophysics and
open activity database, we provide a Calorie estimation approach
that can take into account the human age, gender, weight, height,
step count and duration
• Compared with the output data from miscellaneous website Calorie
calculators, given the same conditions, our approach provides quite
reasonable estimation, which can be easily implemented on
wearable devices equipped with GPS or accelerometer.
• For technical discussion about this sharing, please contact
dibao.wang@gmail.com
• For sensor, SW and technical support, you may visit:
http://www.mcubemems.com/mcube/contact-information/

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Content
• Fundamental
• Biophysical Approach
• Comparison
• Summary

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FUNDAMENTAL

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Physics Unit
• cal (calorie): small calorie or gram calorie
– 1 cal = 4.18 (Joule) … the thermal energy required to raise the temperature of 1
gram water with 1 Deg-C
• Cal: large calorie or kilogram calorie, dietary
calorie, nutritionist's calorie, nutritional calorie,
Calorie (capital C) or food calorie
– 1 Cal = 1 kcal （一大卡）
– 中文使用時，在非正式場合以及非正式書面記錄中，往往將「千卡」、「大卡」
省略為「卡」
• http://en.wikipedia.org/wiki/Calorie
• http://zh.wikipedia.org/wiki/%E5%8D%A1%E8%B7%AF%E9%87%8C

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Empirical Formula
• Ref: Neil Zhao at Analog Device
– http://www.analog.com/library/analogDialogue/china/archives/44-
06/pedometer.html
• Calorie Consumption
• Age, gender height and metabolism are not considered
• C* = 1.25 x (3.6 x Speed)
• Calorie Burn = C* x Weight x Hour

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BIOPHYSICAL APPROACH

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BMR
• BMR (basal metabolic rate)
– Def: the amount of energy required to simply sit/lie quietly for 24
hours
– Or sometimes called, RMR (resting metabolic rate)
– Unit: kcal
– W: weight (kg); H: height (m); A: age (year)
– Basically already determined by your DNAs
• Males: (13.75 x W) + (500 x H) - (6.76 x A) + 66
• Female: (9.56 x W) + (185 x H) - (4.68 x A) + 655
• http://www.shapesense.com/fitness-exercise/calculators/activity-based-calorie-burn-
calculator.aspx#
• http://www.shapesense.com/fitness-exercise/articles/net-versus-gross-calorie-burn.aspx

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BMR
• Age effect
• Weight effect
• Height effect
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BMR(kcal)
Age (yr)
24Hr BMR (W=65kg, H=1.7m)
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Female
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BMR(kcal)
Weight (kg)
24Hr BMR (Age=35yr,H=1.7)
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1.30 1.40 1.50 1.60 1.70 1.80 1.90
BMR(kcal)
Height (m)
24Hr BMR (Age=35yr,W=65kg)
Male
Female

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MET
• MET (Metabolic Equivalent)
– = 1.0 (sit or lie down quietly)
– > 1.0 (other activities); = 0.9 (during sleeping)
– Determined by the activity type associated with
• Definition
– Gross Calorie Burn = (BMR/24) x MET x Duration
– Net Calorie Burn = (BMR/24) x (MET-1) x Duration
• Ref.: The 2011 Compendium of Physical Activities Tracking Guide
(https://sites.google.com/site/compendiumofphysicalactivities/tracking-guide )
• http://www.shapesense.com/fitness-exercise/calculators/activity-based-calorie-burn-calculator.aspx#

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MET
4~163~10 Walk: 2~9.8
Run: 6~23
4~14
• Ref.: The 2011 Compendium of Physical Activities Tracking Guide
(https://sites.google.com/site/compendiumofphysicalactivities/tracking-guide )

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MET
• MET fitting for walking & running
– MET = 0.0006 x S4 - 0.006 x S3 - 0.0865 x S2 + 2.6239 x S - 2.7526
– S (speed) has unit of mph (mile per hour)
– if MET<1.0, MET = 1.0 … to keep the definition of BMR
– Raw data from: The 2011 Compendium of Physical Activities Tracking Guide
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METs
Speed (mph)
Walking
Running
Fitting
For wearables with
• GPS => speed
obtained easily
• Accelerometer only
=> speed estimated
from pedometer via
step counts

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Biophysics
• Step_Width* = 0.052xSR^2 + 0.072xSR + 0.111
– Step_Width = Step_Width* x Height
– SR: step rate (Count/Sec)
– The faster you walk, the larger step width you’ll have
• Speed = SR x Step_Width
– Distance = Step_Cnt x Step_Width
– Speed = Distance / Time_Interval
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StepWidth(dividedbyheight)
Step Rate (Count/sec)

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COMPARISON

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Web Calorie Calculator
• http://www.shapesense.com/fitness-exercise/calculators/activity-
based-calorie-burn-calculator.aspx#
• http://www.freedieting.com/tools/calories_burned.htm
• http://www.mapmyrun.com/improve/calorie_calculator/

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Factor Comparison
Age Gender Weight Height Duration Speed Distance
Emp. Formula
(Analog Device)
V V V
Freedieting.c
om
V V V V V V
ShapeSense
.com
V V V V V V
MapMyrun.c
om
V V V V V V
mCube Inc. V V V V V V

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Speed Effect
• mCube-M represents the estimation of our approach in these two plots above

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Height & Weight Effect
• mCube-M represents the estimation of our approach in these two plots above
• Note: Height effect on Calorie burn is still controversy and thus differs significantly

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Height Effect
• Latest Research (2013) :
– The taller you are, the fewer calories you burn at any given
walking speed. …Still under study!!
– http://www.runnersworld.com/weight-loss/how-height-affects-calorie-burning
– http://www.ncbi.nlm.nih.gov/pubmed/23928111
The simplest version is VO2 = 2 * VO2rest +
5.6 * V^2 / H, where
• VO2 is the total oxygen consumption in
ml/kg/min,
• VO2rest is (essentially) the resting
metabolic rate expressed in ml/kg/min,
• V is the walking speed in m/s, and H is
height in meters.
• 1 MET = 1 cal/kg/hour = 3.5 ml/kg/min.)

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dibao.wang@gmail.com
Currently: Principal SW Engineer,
mCube Inc.