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Measuring body fat

Measuring body fat
In this article I’ll be talking about the different ways to measure your body fat. Actually that isn’t true, because you simply can’t measure your body fat accurately without expensive equipment. What I’m actually going to talk about are the methods that are available that can give you an indication of how much body fat you may have and what is the best methods to monitor it.

If you haven’t already read my article on body fat, where I’ve also touched a little about measuring body fat, please do so here. That article also talks about body fat types, diabetes, how to burn fat and more. I have however written this article, as I wanted to expand a little bit more about measuring body fat to help you reduce and monitor your body fat.


Let’s start by saying that your body actually needs a certain amount of body fat. Your body usually has a certain amount of essential body fat and non essential body fat. Essential body fat is the fat needed to provide long term energy and maintain healthy organs, while non essential is basically excess fat. The problem arises when you store too much of this non essential body fat, leading to an unhealthy body composition and a accumilation of internal bad fats.

Body composition

Your body’s composition will tell you how much of your weight is body fat, but measuring this accurately is very difficult. To do this you need to know what percentage of fat and what percentage of non fat tissue you have (muscles, bones, organs and water etc). To have a healthy body composition you need to have a lower ratio of body fat to non fat tissue.

As a general rule, for men, you should aim for between 10%-20% body fat and for women 16%-27%. At the very least men need to keep their body fat below 24%, while women should keep it below 30%.

With that out of the way I’d like to also mention early on that it’s not just your body fat that is of concern, but more importantly it’s where the fat you have on your body is stored. As mentioned in the body fat article, it’s the deep belly fat (visceral fat) that poses the biggest threat to your health. Unfortunately men tend to get excess fat around the belly as they get older, while women tend to get more around their hips and thighs. However everyone and anyone can easily end up with excess fat around their belly.

To make matter worse is that you can’t spot reduce, so trying to burn off fat  in one spot isn’t going to work, your energy systems and body doesn’t work like that.

Ways employed to monitor body fat:

Bathroom scales

While bathroom scales may be a great way for general weight control, it however doesn’t tell you how much of that weight is body fat or muscle. Nor does it tell us where any body fat is located.

Of course that also then leads us to the argument about weight loss vs fat loss. Many people will go on a diet and lose weight, but along with that is water and often muscle. The problem is while you lose this weight you really don’t want to lose any muscle. Losing muscle can have negative effects on keeping your body fat down. Why? more muscle, means more calories that get burnt for energy, which includes more fat burnt than any other energy source for daily activities. Losing muscle means you burn less calories and a catch 22 situation can occur. Your diet can then back fire as many people can’t sustain a reduced calorie diet for long, then go back to eating normally, struggle to maintain the loss and instead gain the weight back and often even more.

The other issue with using scales is if you are working out you may be building muscle. Muscle weighs four times that of fat per volume, so you may stand on the scales and think you are not losing fat because you are actually building muscle. You simply can’t go by weight alone.

With regards water loss, many diets cause people to lose water and people mistake this weight loss as just fat loss when in fact it is unfortunately probably a high percentage of water. Most people’s weight is made up of 50-65% water, body fat has about 10% water, while muscle has about 75% water. As you can see while your weight and even measurement may go down, a lot of it can be down to water loss rather than fat loss.

Ditch the scales for working out fat loss, but use it to occasionally (maybe once a week) to check your overall weight only.

Body Mass Index

Your body mass index (BMI) is where your height and weight are taken and used to determine if you are at a healthy weight. This doesn’t however tell you the percentage of body fat to muscle mass you have or take into account bone density etc, so is also not a good measure for those that workout and tend to have more muscle mass than the average non trainer.

For those interested, here is how you work out your BMI:


Weight in kilograms divided by height in metres squared

Weight = 168 lbs (76 kilos)

Height = 5′ 8″ (1.7272 metres)

Height squared = 1.7272 x 1.7272 = 2.98 metres

76 ÷ 2.98 = 25.5

So this person has a BMI of 25.5 and therefore just in the overweight category.

  • Underweight = BMI of less than 18.5
  • Normal weight = BMI of 18.5 to 24.9
  • Overweight = BMI of 25 to 29.9
  • Obese = BMI of 30 or greater

Body Adiposity Index

Body Adiposity Index (BAI) is where you take your hip circumference measurement in centimetres, times by your height in metres and then times it by 1.5 and then divide that by 10. This method is said to me more accurate than the BMI method, as it uses your hips as a measure. Your hip measurement is said to be a good indicator of how much body fat you have. But again doesn’t account for muscle mass and all other non fat tissue.


Hip = 39″ (99 cm)

Height = 5′ 8″ (1.7272 meters)

99 x 1.7272 = 171

171 x 1.5 = 256.5

256.6 ÷ 10 = 25.7

Using the same table as the above as the BMI, this person has a BMI of 25.7 which also puts them in the overweight category.

Bioelectrical Impedance Analysis

Bioelectrical Impedance Analysis (BIA). These are the ever popular fat scales. These scales are designed to send an electrical charge through your feet and measure the resistance that will then be able to calculate your water content, BMI, body (muscle) mass, body fat, bone mass, Basal Metabolic Rate (BMR) and even more data with some of the more expensive scales.

The down side to this is that the results can be dependent on whether you are hydrated or not and it only measures the resistance through your lower body. Along with calculations again based on height and weight, these tend to give variable results and are often inaccurate.

Hydrostatic weighing

This is where you are placed under water, muscle and bone mass is heavier in water, fat mass is lighter, so this method can be a reasonably accurate way to calculate body fat. However it is expensive and impractical for regular monitoring.

Other expensive devices for measuring fat

There are other devices that I know nothing about, such as the Bod Pod and Dexa scan, but like hydrostatic measurements are mostly beyond the reach of most people due to the speciality and expense of these devices and so see no point in saying anymore than just mentioning them for the purpose of this article.

Skin fold calipers

These are used to pinch certain areas of the body to calculate your body fat. The caliper when pinched around a specific body part has a scale that will measure the thickness of that area, that when used against the provided chart along with your age, gender and height will indicate what percentage of body fat you have. This can be quite a reasonable way to get an idea of your overall body fat. It is cheap to buy, small and compact.

However you need to use the same areas each time in exactly the same way to be reasonably accurate. Otherwise it can give you quite inconsistent measurements.

Tape measure

Around the waist – using a tape measure around your waist can be a good way for monitoring that mid section for fat loss. Muscle doesn’t tend to build around the mid section as much as other areas so a waist measurement can give you a good way to monitor fat loss in general.

Waist to hip ratio – Alternatively you can measure your waist to hip ratio. To do this, measure your waist just above your belly button and then measure your hip at its widest. Then divide your waist measurement by your hip measurement.


Waist = 34″ (86 cm)

Hip = 39″ (99 cm)

86 ÷ 99 = 0.87

This person therefore falls in the normal weight category for a man or in the obese category for a women.

< 0.90              normal weight
0.90 to 0.99     over-weight
1.0+                 obesity

< 0.80              normal weight
0.80 to 0.84     over-weight
0.85+               obesity

String method

This method uses a piece of string to measure your height. You then fold the string in half and to be within a healthy range the string should be able to go around your waist and touch ends. Therefore your waist should not be more than double your height. This will help see if you are carrying excess weight around your belly and leave out such things as muscle mass and bone density. It has however been found to be a good indicator for most people to see if they are on the right side of the healthy waist to height ratio with belly fat being the biggest factor for bad fat accumulation.


Looking in the mirror can work for many, but don’t expect to see daily changes. The changes to your body may be much slower than you notice so looking in the mirror too often can be demotivating if you don’t notice any changes.


Taking a picture can work better for some, especially if you take them once a month. Make sure you take the picture in the same light, area, angle and preferably in the same physical state (not just had a workout, pumped up etc), so you are taking the image under the same conditions each time.


So what do I recommend? well the good news is that I recommend you use the cheaper methods, such as the skin fold calipers, tape measure, string method and mirror and/or pictures. Anyone or a combination of any of these will serve you well in monitoring progress for fat loss.

The reality is you are not going to get an accurate reading for your body fat without using one of the much more expensive methods. However your goal should be to reduce your overall waist size. This is the easiest way to monitor a reduction in body fat. Bad fat is deep inside and mostly located in your mid section, you can’t pinch it to measure it. It is around your organs, but reducing your belly fat, you will also reduce this fat and reducing your waist circumference will reduce both fats.

What’s more important is that you have a base line to work from and that you can see results going in the right direction.

Lastly start working out and either try to maintain or build some muscle, which will all help.