DEXA vs Navy Method: Which Should You Use?
Comparing the gold standard with a free at-home method
Key Insight
DEXA is more accurate but expensive and less accessible. The Navy method is free and good for tracking trends. For most people, consistent Navy measurements are sufficient.
Method Comparison
| Aspect | DEXA | Navy Method |
|---|---|---|
| Accuracy | ±1-2% error | ±3-4% error |
| Cost | $50-150 per scan | Free (just need tape measure) |
| Accessibility | Requires clinic visit | Can do at home anytime |
| Measurement Frequency | Every 3-6 months recommended | Weekly or as needed |
| Best For | Baseline and periodic validation | Regular progress tracking |
What Is DEXA?
DEXA (Dual-Energy X-ray Absorptiometry) uses low-dose X-rays to measure bone density, fat mass, and lean mass. It's considered the gold standard for body composition analysis, providing detailed regional breakdown of where fat is stored. However, results can still vary based on hydration, recent meals, and the specific machine used.
What Is the Navy Method?
The U.S. Navy method estimates body fat using circumference measurements (neck, waist, and hips for women). It was developed for military fitness assessments and provides reasonably accurate estimates for most body types. While less precise than DEXA, it's free, accessible, and excellent for tracking changes over time.
When to Use Each Method
Use DEXA for establishing an accurate baseline, validating your Navy measurements periodically, or when you need precise data (competitions, medical reasons). Use the Navy method for regular progress tracking, when DEXA isn't accessible or affordable, and for monitoring trends over time. Many people use both: DEXA every 3-6 months with Navy measurements weekly.
Frequently Asked Questions
Is DEXA the most accurate body fat test?
DEXA is among the most accurate practical methods, but even it has 1-2% error. Hydrostatic weighing and 4-compartment models may be slightly more accurate but are less accessible.
How far off can Navy method be from DEXA?
The Navy method can differ from DEXA by 3-5% in either direction. However, it's consistent enough to track changes over time reliably.
Is DEXA worth the cost?
For most people, occasional DEXA scans (1-2 per year) combined with regular Navy measurements provide good value. DEXA is more valuable if you need precise data.
Can I calibrate Navy measurements using DEXA?
Yes, getting a DEXA scan helps you understand how your Navy measurements compare to a more accurate method, allowing you to interpret your results better.
Why do different methods give different results?
Each method measures different things and has different error sources. Focus on trends within one method rather than comparing absolute numbers across methods.
What method should athletes use?
Athletes benefit from periodic DEXA scans for accurate data, with Navy or skinfold measurements for regular tracking. The Navy method may underestimate body fat in very muscular individuals.