DEXA scans are highly reproducible, but food intake, hydration, exercise, and other factors can temporarily affect body-composition measurements. Our recommendations are intended to give you the most reliable baseline and, especially for follow-up scans, allow us to compare results under similar conditions. If you cannot meet every recommendation, you are still a candidate for scanning. Simply let us know what was different so we can direct you on having consistent conditions for our follow-up scan.
Body Composition DEXA
Food: Avoid eating for 3–4 hours before your scan. An overnight fast is not necessary. A large meal or binge the day before can increase body weight and gastrointestinal contents and may introduce additional variability.
Diet: Consuming high amounts of carbohydrates can artificially increase lean-mass measurements. Maintain a routine eating pattern before testing, and ensure repeat evaluations take place under comparable dietary conditions for optimal comparison.
Hydration: Arrive normally hydrated. Avoid intentionally dehydrating yourself or consuming unusually large amounts of fluid before the scan. Significant changes in hydration can affect the measurement of lean mass.
Exercise: Avoid strenuous exercise for approximately 12 hours before your scan. Exercise can temporarily alter muscle glycogen, tissue water, and fluid distribution, potentially affecting lean-mass measurements.
Clothing: Wear lightweight clothing with minimal or no metal.
Consistency: For repeat scans, try to duplicate your previous scan conditions including approximate time of day, fasting status, hydration, and exercise, to the best of our ability.
Bone Density Scan Preparation
Food & hydration: No fasting is required. Eat and drink normally.
Calcium supplements: Avoid calcium supplements and calcium-containing antacids for 24 hours before your scan, when possible. Normal dietary calcium is fine. Calcium remaining in the digestive tract can interfere with the measurement.
Exercise: No specific exercise restriction is generally required for bone-density testing.
Clothing: Wear comfortable clothing with minimal or no metal. Gowns are available if needed.
Recent imaging: If you have had recent imaging involving barium, oral contrast, or nuclear medicine/radiologic contrast, within the last 2 weeks, your scan must be postponed as residual material can interfere with DXA measurements.
Unable to follow the recommendations? You can generally still be scanned. Let us know what was different so we can document the conditions and determine whether the scan should proceed or be rescheduled.
Resources
- Tinsley GM, Morales E, Forsse JS, Grandjean PW. Impact of Acute Dietary Manipulations on DXA and BIA Body Composition Estimates. Med Sci Sports Exerc. 2017 Apr;49(4):823-832. doi: 10.1249/MSS.0000000000001148. PMID: 27875499.
- Gallagher D, Heymsfield SB, Heo M, Jebb SA, Murgatroyd PR, Sakamoto Y. Healthy percentage body fat ranges: an approach for developing guidelines based on body mass index. Am J Clin Nutr. 2000 Sep;72(3):694-701. doi: 10.1093/ajcn/72.3.694. PMID: 10966886.
- Bone JL, Ross ML, Tomcik KA, Jeacocke NA, Hopkins WG, Burke LM. Manipulation of Muscle Creatine and Glycogen Changes Dual X-ray Absorptiometry Estimates of Body Composition. Med Sci Sports Exerc. 2017 May;49(5):1029-1035. doi: 10.1249/MSS.0000000000001174. PMID: 28410328.
- Nana A, Slater GJ, Hopkins WG, Burke LM. Effects of daily activities on dual-energy X-ray absorptiometry measurements of body composition in active people. Med Sci Sports Exerc. 2012 Jan;44(1):180-9. doi: 10.1249/MSS.0b013e318228b60e. PMID: 22179140.
- Nana A, Slater GJ, Hopkins WG, Burke LM. Effects of exercise sessions on DXA measurements of body composition in active people. Med Sci Sports Exerc. 2013 Jan;45(1):178-85. doi: 10.1249/MSS.0b013e31826c9cfd. PMID: 22895377.
- Toomey CM, McCormack WG, Jakeman P. The effect of hydration status on the measurement of lean tissue mass by dual-energy X-ray absorptiometry. Eur J Appl Physiol. 2017 Mar;117(3):567-574. doi: 10.1007/s00421-017-3552-x. Epub 2017 Feb 16. PMID: 28204901.