How to prepare for your DEXA scan
A DEXA scan is a precise and highly accurate way to measure your body composition.
Please follow the pre-scan advice below
Because your body is a dynamic biological system which is constantly adapting to inputs like nutrition, hydration, and exercise, its composition can fluctuate throughout the day. Lean mass can be affected by water weight from changing glycogen levels and recent exercise.
To ensure that any differences between your scans reflect real progress and not temporary shifts, it is important to standardise conditions before each appointment.
Fast before your scan
Ideally you will be fully fasted before your scan to reduce variability from recent meals. We want to measure your body, not what you are digesting.
If your scan is in the morning, it is best to fast until your scan. If it is later in the day then you should be fasted for 2 - 4 hours prior to your scan.
Additionally, emptying your bladder prior to a scan is recommended.Refrain from heavy exercise
Avoid intense exercise in the 12 hours before your scan, especially resistance training. Post-workout pumps are short-term fluid shifts which increase lean muscle size. We want your muscles to be rested so that we can measure them in a consistent state for each scan.
Wear light, comfortable clothing
Avoid elasticated clothing to prevent image distortion, we want your body to position naturally on the scanner bed.
Also avoid clothing with metal (no zippers, buttons, or underwire bras).Remove all metal (jewellery, watches etc)
Metals will create interference in your scan and affect the accuracy of the readings for each tissue. Remove all metal where possible.
If you have metal implants inside your body then we can still scan you. The X-rays will not cause metal to heat up or pose any risk to you.
Further advice to consider to achieve the most accurate results
Keep carbohydrate intake consistent in the days leading up to your scan, high carb intake increases muscle glycogen stores, each gram of which binds 3-4 grams of water, potentially inflating lean mass readings by several kilograms. If you are a professional athlete then you may wish to record your nutrition and meals in the lead up to your scan to ensure consistency for future scans. This is not necessary however.
Stay well-hydrated in the days before the scan, but avoid drinking large amounts of water immediately beforehand.
Avoid alcohol and high-sodium foods the night before to minimise fluid retention, which can skew lean mass measurements.
Scheduling scans at a consistent time of day for repeat assessments will make it easier to ensure consistency in preparation (i.e. first thing in the morning before exercise).
Avoid calcium supplements for at least 24 hours before your scan, as they can interfere with bone density readings.
Tracking Over Time? Consistency Is Key.
A DEXA scan is highly precise, measuring exactly the human body as it is presented for the scan. If you intend to scan regularly to track changes in your composition over time, consistency is key.
Your lean mass and total body weight are sensitive to temporary fluctuations in hydration, glycogen storage, and stomach content.
To ensure your results reflect true tissue changes rather than daily shifts, we recommend recording and replicating your nutrition, hydration, exercise, for the 48 hours prior to each appointment. By following the same pre-scan protocol every time, you ensure a like-for-like comparison that captures your genuine progress.
Measured data,
not guesswork.
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