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The best way to measure body fat levels

For years, BMI was the recognised way clinicians calculated whether a person’s weight is healthy or unhealthy. But the advent of the DEXA scanner has changed all of this.

The accurate way to discover your body composition

  • The DEXA scan is best known for its super-accurate method of detecting the risk of osteoporosis. A DEXA measurement compares and calculates your bone density to other people who are the same age and sex, giving a good indication as to whether you’re at risk of osteoporosis.
  • A DEXA scanner with advanced diagnostic features such as ‘Advanced Body Composition’ software, can provide a reading of the total fat in the trunk area of your body. Too much fat around the middle is a risk factor for heart disease.
  • The DEXA with the ‘Core Scan’ option gives even greater precision. A DEXA core scan identifies whether the fat is visceral variety – which accumulates around the internal organs such as the liver, pancreas and intestines – risk factors for diabetes, heart disease and cancer rise.


This is a safe and non-invasive treatment, with the advantage of using a far lower radiation level than CT scan or MRIs. You don’t need to be referred to a doctor. You can walk into a clinic and discover whether you are at risk of heart disease, diabetes and cancer – which will allow you to make the alterations in your lifestyle to slash your risk.

Twenty-five Harley Street offers two Body Composition scans for £220 – so you can choose to have one scan to find out your true fat levels. Then after a nutrition and exercise regime, you can have another scan and find out whether you have managed to cut the dangerous levels of body fat again.

You can also have a DEXA scan performed as part of a health screening or check.

How is a DEXA performed?

You will wear a gown for the procedure and remove jewellery. The scan is on an open table, so you won’t need to feel closed in, like an MRI. You will need to stay still, so the technician may use fasteners to keep you in place. The scan itself takes just a few minutes. You should be all done within 15 minutes.

How does the technology behind DEXA scan work?

Two X-ray beams with different energy levels are aimed at the patient’s bones. Some of the radiation is taken in by the bone and soft tissue and some travels through your body.

The DEXA scanner works out how much radiation is being passed through your bones by directing X-ray energy through the bone at a very fast rate, alternating from two different sources. This allows the scanner to work out your bone density.

In terms of soft tissue measurements (fat and lean body mass) it is measured in areas where there is no bone is present.

Is DEXA a better measurement than BMI?

Yes – BMI is an outdated term, because it sees weight itself as unhealthy. BMI refers to your weight in kilograms divided by height in metres, and divided by height again. Below 18.5 is classified as underweight, over 25 is overweight. Over 30 means you’re in the obese category.

In fact, it is fat that is unhealthy. A muscular boxer may well weigh more than a person carrying too much fat. But who is the more healthy? The body composition scan leaves no room for doubt that the ‘over-weight’ athlete is the healthiest. In other words, we should all be aware of being over fat, rather than overweight.

An ideal body composition should be the correct amount of fat for a person of our age, sex and ethnicity. A body composition scan with DEXA can reveal this.

Are there other ways to measure body fat?

There are – some are low tech, others like hydrostatic weighing aren’t for everyone. Here is  round-up:

Waist circumference. Measure your waist is halfway between your lowest rib and the top of your hipbone. This is roughly in line with your belly button. If you are female and you have a measurement of 80 cm or more your risk of conditions like heart disease and diabetes is elevated. If it’s 88cm or more, it’s high. If you are a man your risk of health problems rises at is 94 cm or more and is high at 102 cm or more. This form of measurement is still not as accurate as DEXA and doesn’t work for all ethnicities.

Skin Calipers. As the TV advert used to say ‘Can you pinch more than an inch?’ Skin calipers make skin fold assessment in three, four or seven place in the body. Each place has an optimal ‘pinch’. The caliper devise measures the thickness of the skin fold and compares it to the optimal measurement.  However, there is a big margin for error can vary depending on the person measuring.

Hydrostatic Weighing. Like DEXA, this is a super-accurate form of measuring: unlike DEXA, it’s not simple or hassle free. Hydrostatic weighing – or underwater weighing, weights a person outside the water and then while completely submerged. By calculating the weights and the density of the water, body composition can be worked out. Not recommended for those with a fear of water or claustrophobia!

Where can I make an appointment for DEXA?

Twenty-five Harley Street offers the most advanced DEXA scanning available. Choose from our special offer for fitness where you have two Body Composition Scans for £220 so you can compare before and after training, or a DEXA Scan with a Bone Density report and Body Composition report with the UK’s leading medical expert on DEXA, Professor Reid for £450.