Medically reviewed by Dr. Numair Younis, M.B.B.S. (K.E.M.U.), FEBNM European Fellowship in Nuclear Medicine, Consultant Nuclear Medicine Physician, Al-Nasar Lab & Diagnostic Centre. Updated August 2026.
Quick answer: A DEXA body composition scan measures exactly how much of your body is fat, muscle and bone, and shows where that fat is stored. It is the reference standard for body composition, far more precise than BMI or a smart scale, and it is the only routine scan that separates dangerous visceral fat from harmless fat under the skin.
Book a body composition scan: call 0300 0341944 or request an appointment.
What is a DEXA body composition scan?
It uses the same scanner as a bone density DEXA scan, but analysed differently. Two low dose X-ray beams pass through the body, and because fat, lean tissue and bone each absorb them differently, the machine can calculate precisely how much of each you have.
The result is not a single number. It is a full breakdown of your body, arm by arm, leg by leg, and through the trunk, showing where fat and muscle actually sit rather than just how much you weigh.
Why is the bathroom scale not enough?
A weighing scale tells you how much you weigh. It cannot tell you what that weight is made of, and that distinction is where almost all the useful information lives.
Two people of identical height and weight can have completely different health outlooks: one carrying substantial muscle and little abdominal fat, the other carrying little muscle and a great deal of it. BMI treats them as identical. So does the scale. A DEXA scan does not.
| Method | What it actually measures | Accuracy |
|---|---|---|
| BMI | Weight against height. Nothing else | Very rough. Cannot separate fat from muscle |
| Smart scale (bioimpedance) | Estimates fat by passing a small current through the body | Variable. Readings shift with hydration, food and time of day |
| Skinfold calipers | Fat directly under the skin at a few points | Depends heavily on who is measuring. Cannot see internal fat |
| Waist measurement | Abdominal size | Useful and free, but cannot separate visceral from subcutaneous fat |
| DEXA | Fat, lean mass and bone, measured region by region | The reference standard. Precise enough to track small changes |
What is visceral fat and why does it matter?
Not all fat carries the same risk. Fat sitting just beneath the skin, which you can pinch, is relatively harmless. Visceral fat is different. It wraps around the organs inside the abdomen, and it is metabolically active, releasing substances that drive insulin resistance, inflammation and raised blood pressure.
This is why some people with an unremarkable weight still develop type 2 diabetes and heart disease, while others who look heavier stay metabolically healthy. The visible fat was never the problem. A DEXA scan gives a direct measurement of visceral fat, which no scale and no tape measure can provide.
Why does this matter particularly in Pakistan?
South Asian populations tend to carry a higher proportion of body fat, and notably more visceral fat, at any given BMI than European populations. The BMI thresholds most people know were not derived from South Asian bodies, which means a Pakistani adult can sit within a supposedly normal BMI while carrying a metabolically risky amount of internal fat.
Combined with one of the highest diabetes rates in the world, that makes measurement rather than assumption genuinely important. A DEXA body composition scan alongside an HbA1c test gives a far clearer picture of metabolic risk than weight and blood sugar considered separately.
What does the report show you?
- Total body fat percentage and total fat mass in kilograms
- Lean mass, which is essentially your muscle, broken down by each arm, each leg and the trunk
- Visceral fat in the abdominal cavity
- Android and gynoid distribution, meaning fat around the waist compared with fat around the hips and thighs. The ratio between them is a recognised marker of metabolic risk
- Bone mineral content, measured at the same time
- Left to right symmetry, which is useful after injury or during rehabilitation
Who should have a body composition scan?
- Anyone losing weight who wants to know whether they are losing fat or muscle. Rapid weight loss often costs muscle, and the scale cannot tell you
- People with diabetes, prediabetes or a family history of it, to measure visceral fat directly
- Athletes and serious trainers tracking whether a training block is producing muscle
- Older adults, where gradual muscle loss, known as sarcopenia, quietly increases the risk of falls and frailty
- People with a normal BMI but a large waist, who are often reassured by a scale that is measuring the wrong thing
- Anyone recovering from illness or surgery, to track whether lean mass is being regained
How do you prepare?
- Wear comfortable clothing without metal. Zips, buttons, underwiring and hooks all interfere
- Avoid calcium supplements for around 24 hours beforehand
- Tell the team if you have had a barium study, CT contrast or nuclear medicine scan in the past week
- Tell staff if you are, or might be, pregnant
- For repeat scans, keep conditions consistent. Same time of day, similar hydration, and ideally not straight after a large meal or a hard training session. Consistency is what makes the comparison meaningful
How often should you repeat it?
Body composition changes slowly. Scanning too often produces differences too small to interpret and encourages reacting to noise. For most people every three to six months is appropriate. Athletes in structured training blocks may scan more frequently, and anyone in a supervised weight loss or rehabilitation programme should follow the interval their clinician sets.
Is it safe?
Yes. The radiation dose is very low, considerably less than a standard chest X-ray and comparable to the natural background radiation you receive in an ordinary day. The scan is painless, nothing touches you, and there is no enclosed tunnel, so it suits people who find MRI difficult. It takes around 10 to 15 minutes.
Body composition scanning at Al-Nasar Lab
Al-Nasar Lab & Diagnostic Centre provides DEXA body composition analysis at its main Johar Town campus, alongside bone density scanning, X-ray, CT, MRI, ultrasound and nuclear medicine. Scans are reported by qualified consultants, and related tests such as HbA1c, lipid profile, thyroid function and vitamin D can be arranged at the same visit, which is usually exactly what a doctor wants alongside a body composition result.
Explore our full test list, find your nearest branch, or call 0300 0341944 to book.
Frequently Asked Questions
How accurate is a DEXA body composition scan?
It is regarded as the reference standard in clinical practice and research, and is precise enough to detect changes that a smart scale or calipers would miss entirely.
Is DEXA better than a smart scale for body fat?
Considerably. Smart scales estimate fat by passing a current through the body, so readings move with hydration, food and time of day. DEXA measures tissue directly and reports it region by region.
Does a body composition scan hurt?
No. You lie still, fully clothed, on a padded table while the scanning arm passes above you. Nothing touches or enters the body.
Can it tell me if I am losing fat or muscle?
Yes, and that is one of its most valuable uses. Two scans a few months apart show precisely how much of any weight change was fat and how much was lean mass.
Is this the same as a bone density scan?
The same machine is used, but the analysis differs. A bone density scan assesses fracture risk. A body composition scan measures fat, muscle and their distribution. Both can often be performed in the same visit.
This article is for general information and is not a substitute for medical advice. Please discuss your results with a qualified doctor.
