Measuring Fitness
When starting a new weight loss plan, or body building and workout routine, it's helpful to track your progress with different measures of fitness and health. The fitness indicators described below use height, weight, age, heart rate, skinfold thickness, and other body measurements to show you what you need to work on to get in shape. The only tools needed are a scale, tape measure, pair of calipers, and a scientific calculator.
You can also program all of the formulas in to Excel to create a fitness tracking spreadsheet. Or, if you don't like doing the math, you can just use various online calculators to compute all the values. To skip all of the explanations for the formulas, scroll down to the bottom for a complete list of equations.
You can also program all of the formulas in to Excel to create a fitness tracking spreadsheet. Or, if you don't like doing the math, you can just use various online calculators to compute all the values. To skip all of the explanations for the formulas, scroll down to the bottom for a complete list of equations.
Contents
Body Mass Index--BMI
the most commonly used (and overused) measure
The Body Mass Index, BMI for short, is the gold standard for simple, easy to use measures of general health and fitness. You only need two body measurements to calculate BMI--your weight and height--and it's pretty easy to interpret; very low BMIs correspond to being underweight, very high BMIs correspond to being overweight or obese, and healthy people are somewhere in the middle. BMI is ubiquitous; even the World Health Organization uses it famine statistics.But, like anything that is too easy, there are drawbacks. One major criticism of BMI is that it doesn't take into account body composition and distribution of mass. Obviously, since muscle is heavier than fat, body builders have high BMIs, while a pudgy person could actually have a surprisingly low BMI. Where body mass is distributed also affects health. The picture shows 8 women who all have BMI values of 30, but widely different body types. The one on the far left is likely the unhealthiest of the bunch.
Body Mass Index is calculated by this formula for height in inches (H) and weight in pounds (W):
BMI = (703)(W)/(H²)
Or use this formula for weight in kg and height in cm:
BMI = W/(H²)
And this is the scale used to interpret it:
< 18.5 underweight
18.5-24.9 healthy
25-30 overweight
> 30 obese
Even though BMI doesn't take into account anything besides weight and height, in the absence of other measurements, it can be used to roughly approximate other indicators of health, such as lean body mass and basal metabolic rate. Read about these other uses of BMI for more info. Also check out Using BMI to Calculate Ideal Body Weight.
Body Fat & Lean Body Mass
Three interrelated health measurements are total body fat, percent body fat, and lean body mass (LBM). Total body fat is the total weight of fat in your body. Percent body fat is the percentage of your weight that is fat. And lean body mass is the total weight of non-fat tissue in your body. For example, if a woman weighs 140 lbs and has 30 lbs of fat, thentotal body fat = 30 lbs
% body fat = 30/140 = .214, or 21.4%
lean body mass = 140 - 30 = 110 lbs
There are many ways to compute the numbers. The traditional technique of determining how much fat a person has is by hydrostatic testing. Your body is submerged in a tank of water and your buoyancy is used to determine percentage body fat. The principle behind this method is the fact that fat floats in water. So, the more buoyant you are, the higher your percent body fat. This also gives the truest estimate of % body fat.
In lieu of of hydrostatic measurement (which is costly) you can also compute body fat with these methods.
Skinfold Analysis: Thickness of subcutaneous fat (the fat under your skin) is another predictor of fat. The traditional way to do this is to use calipers to record the thickness of folds on seven areas of the body, add them all up, and then plug that sum into an equation. Read Using Calipers to Take the 7 Skin Fold Measurements for a detailed guide on using calipers correctly. And then read Formulas for Calculating Body Fat with Skin Fold Measurements to compute the final numbers.
Girth Methods for Men: For men, body fat can be estimate by the circumference of the waist and neck, relative to weight and height. This article on calculating male body fat with two methods describes a couple of formulas. The first formula considers waist girth and weight; the second considers waist & neck girth plus height.
Girth Methods for Women: This article explains how to calculate female body fat with waist, wrist, hip, and forearm circumferences. The equation is very simple, all you need is a tape measure.
All these formulas were developed and tested by scientists. When the equation results are compared to the hydrostatic testing results, they accurate within 5%.
Weightloss Tools
Everything you need to chart changes in total body fat, percent body fat, and lean body mass, plus diet and exercise helpers.
Basal Metabolic Rate--BMR
minumum daily calorie needs
You metabolic rate, aka metabolism, is the rate at which you burn calories as you expend energy during the day. To have a high metabolism is a good thing from a weight loss standpoint, since it means that your work outs burn a lot of calories. A lower metabolism is not such a good thing for losing weight, since it means more exercise is needed to burn off calories. The golden rule for weight loss is that you must burn more calories than you consume.
The calories we see on food labels are actually kilocalories, units of 1000 calories, but in common speech, everyone just calls kilocalories "calories."
What is the basal metabolic rate? Your BMR is the number of calories you would burn in a day if you did absolutely nothing but sleep for the 24 hours. No moving, no snoring, no dreaming. It's the number of calories a comatose person would need to maintain his current weight. Of course, people who are awake for part of the day will need to eat more calories than their BMR value! How much more depends on activity level.
Let's say that your BMR is X calories. Then the number of calories you need to take in is X multiplied by a factor between 1.2 and 1.9. 1.2 represents the low end of the activity scale, and 1.9 the upper end.
You can find what X is with this formula for computing BMR. The article also tells you which number to multiply by to find your daily calorie needs.
And this article explains how to estimate BMR with BMI.
The calories we see on food labels are actually kilocalories, units of 1000 calories, but in common speech, everyone just calls kilocalories "calories."
What is the basal metabolic rate? Your BMR is the number of calories you would burn in a day if you did absolutely nothing but sleep for the 24 hours. No moving, no snoring, no dreaming. It's the number of calories a comatose person would need to maintain his current weight. Of course, people who are awake for part of the day will need to eat more calories than their BMR value! How much more depends on activity level.
Let's say that your BMR is X calories. Then the number of calories you need to take in is X multiplied by a factor between 1.2 and 1.9. 1.2 represents the low end of the activity scale, and 1.9 the upper end.
You can find what X is with this formula for computing BMR. The article also tells you which number to multiply by to find your daily calorie needs.
And this article explains how to estimate BMR with BMI.
Heart Rate Training Zone
using pusle to find the optimum intesity level of exercise
In order to burn calories and lose weight more efficiently, one must exercise at the right intensity level. Too low, and you won't get an effective work out or burn fat reserves. Exercising at an extremely high intensity is great if you are already in shape, but it won't effectively burn fat if you are just beginning a regimen and have a lot of pounds to shed.The right intensity level can be determined by your heart rate during a work out. When you are exercising at 60%-85% of the maximum intensity level, your heart rate is said to be in the "training zone." The training zone is a range of heart rates; the upper and lower ends of the range depend on your maximum heart rate (MHR) and your resting heart rate (RHR) measured in beats per minute (bpm).
Read How to Calculate MHR and the Training Zone with the Karvonen Formula for a set of simple equations that will determine your bmp range.
Heart Rate Helpers
Body Surface Area
just for fun
Okay, body surface area doesn't have much to do with fitness and weight loss, other than the fact that as you become skinnier and more fit, your total surface area will decrease. But if you are curious, you can read this article on calculating body surface area.
List of Equations
in case you don't want to read all that stuff up there
- BMI = 703W/H² [ H=inches and W=pounds ]
- BMI = W/H² [ H=cm and W=kg ]
- male body density = 1.112 - (.000435)F + (.00000055)F² - (.000288)A
[ F = skinfold thickness in mm, A = age in years ] - Navy method
male body density = 1.01774 - .19077LOG(W-N) + .15456LOG(H)
[ W, N, & H =waist girth, neck girth, & height in inches ] - female body density = 1.097 - (.00047)F + (.00000056)F² - (.000128)A
[ F = skinfold thickness in mm, A = age in years ] - male lean body mass in pounds, LBM = 94.42 - 4.15X + 1.082Y
[ X=waist inches, Y=weight lbs ] - female lean body mass in pounds, LBM =
.732A - .157B + .318C - .249D + .434E + 8.987
[ A=weight lbs. B, C, D, & E = waist, wrist, hip, & forearm inches ] - LBM estimated with BMI
LBM men = (1.1)W[1 - (.011636)BMI]
LBM women = (1.07)W[1 - (.013832)BMI]
[ W=weight, any units ] - Total Body Fat + LMB = Total Weight
- LBM = Weight x (1 - P), P = % Body Fat, as a decimal
- % Body Fat = (Total Body Fat)/(Total Weight)
- % Body Fat Men = 495/(Body Density) - 450
- % Body Fat Women = 496/(Body Density) - 451
- male BMR = BMR = 6.24W + 12.71H - 6.76A + 66.47
[ W=weight lbs, H=height inches, A=age years ] - female BMR = 4.34W + 4.7H - 4.68A + 655.1
[ W=weight lbs, H=height inches, A=age years ] - Alternative BMR formula
BMR m= (4.5306)W + (15.875)H - (4.92)A + 5
BMR f = (4.5306)W + (15.875)H - (4.92)A - 161
[ W=weight lbs, H=height inches, A=age years ] - BMR male or female = 370 + (9.795)LBM
[ LBM in lbs ] - 4 Maximum Heart Rate Formulas
MHR = 220 - A
MHR = 217 - (0.85)A
MHR = 206.3 - (0.711)A
MHR = 205.8 - (0.685)A
[ A=age years ] - Training Zone Heart Rate
Upper End = (0.85)MHR + (.15)RHR
Lower End = (0.6)MHR + (0.4)RHR
[ RHR = resting heart rate in beats per minute ] - 4 Formulas for Body Surface Area in square meters
BSA = [W^(0.5)][H^(0.5)]/60
BSA = [W^(0.425)][H^(0.725)]/139.2
BSA = [W^(0.51456)][H^(0.42246)]/42.5532
BSA = [W^(0.5378)][H^(0.3964)]/41.2116
[ W=weight in kg, H=height in cm ] - Another BSA Formula
BSA = [W^(P)][H^(0.3)]/3118.179
where P = 0.7285 - 0.0188Log(W)
[ W in grams, H in cm ]
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