DEXA vs Tape Measures vs Scales

Too often, people start going to the gym, begin a new training program and diet, but never truly know if it worked. This is because it can be difficult to determine whether a weight change has come from muscle gain, fat loss, or something else entirely.

Here’s what we know:

• Tracking muscle gain can be frustrating – weight may stay the same, and visual changes are slow.
  
• Tools like tape measures and bathroom scales offer some insight, but they don’t tell the full story.
  

So let’s dig a little deeper into the most common methods of tracking muscle gain and explain why DEXA scanning is the most precise option available.

Bathroom Scales

Most households have a set of scales somewhere. Whether they’re used for luggage before a holiday or to track daily weight, they’re a familiar tool to everyone. Scales vary widely – digital, spring-loaded, or professionally calibrated. Overall, they can cost anywhere from $20 to well over $100.

Pros:

• Cheap and easy to use.
  
• Helpful for tracking general weight trends.
  

Cons:

• Can’t differentiate between fat, muscle, bones or water weight.
  
• Doesn’t reflect changes in body composition.
  
• Can lead to over-focusing on the number alone.
  

Smart Scales

Smart scales are modern bathroom or fitness scales that go beyond simply measuring weight. They use advanced sensors and bioelectrical impedance analysis (BIA) to estimate body composition metrics such as body fat percentage and muscle mass.

However, it’s important to remember that these measurements are less precise than other methods, as factors like hydration levels, recent meals, exercise, and even skin temperature can cause noticeable fluctuations from day to day, making the readings more useful for observing long-term trends rather than exact daily values.

2. Tape Measurements

Using a tape measure to assess the circumference of body parts (like arms, chest, or thighs) can be helpful for tracking growth. However, it doesn’t always tell the full story. For example, a 3cm increase in bicep size over six weeks could be muscle mass or fat mass.

Pros:

• Useful for tracking changes in specific areas
  
• Inexpensive and accessible
  

Cons:

• Doesn’t distinguish fat gain from muscle gain
  
• Easy to mismeasure or be inconsistent
  
• May miss subtle yet meaningful body composition changes
  

3. Dual-Energy X-ray Absorptiometry (DEXA) Scans

DEXA scans are the gold standard for measuring body composition. This non-invasive, painless scan uses low-dose X-rays at two energy levels to differentiate between bone, fat, and lean tissue.

Pros:

• Most accurate method for measuring lean mass, fat mass, and bone density.
  
• Tracks changes in specific regions (e.g. arms vs. legs).
  
• Measures visceral fat and muscle separately.
  
• Highly reproducible.
  
• Scans only take ~4 minutes and are non-invasive.
  

Cons:

• Requires a clinic appointment.
  
• Generally higher cost than other methods.
  

Below is a case example of where the scale weight was relatively unchanged (-1.1kg total), but the DEXA scan revealed significant shifts in muscle and fat composition beneath the surface (almost 10kg total change).

Why Muscle Tracking Matters

Tracking muscle mass gives you deeper insight into your health—not just aesthetics or strength. As we age, we naturally lose muscle mass, which can impact mobility, metabolism, and longevity. Monitoring these changes helps guide your training and nutrition plans to minimise loss and support long-term health.

For athletes (e.g. combat athletes, powerlifters, CrossFitters, and field sport players), precise tracking helps:

• Manage weight for competition.
  
• Maximise strength and performance.
  
• Measures if you’re gaining lean mass – not just weight.
  

How Often Should You Measure?

Building muscle doesn’t happen overnight – it’s a long-term process. That’s why daily or weekly measurements aren’t necessary or helpful. Instead:

• Every ~12 weeks is ideal for meaningful muscle tracking.
  
• Combine DEXA with progress photos and strength benchmarks.
  
• Use consistent intervals to assess your training and nutrition plan’s effectiveness.
  

Comparison Table

Method	Pros	Cons
Scales	Cheap, easy, tracks overall weight trends.	Doesn’t show fat vs muscle, misleading changes. Advanced ‘smart scales’ can be inaccurate and vary day-to-day with body composition data.
Tape Measure	Inexpensive, tracks specific area changes.	Inconsistent, doesn’t separate fat/muscle.
DEXA Scan	Gold standard, precise, region-specific data	Requires a clinic visit, higher cost.

Conclusion

Scales and tape measures can offer a general sense of progress 0 but they often miss what’s happening beneath the surface. If you’re serious about building muscle, improving performance, or optimising your health, you need accurate, objective data.

DEXA scans provide the clearest, most precise insight into your body composition- tracking fat, muscle, and bone mineral density with accurate results.

By measuring every ~12 weeks, you’ll be able to adjust your training and diet with confidence, and know your hard work is producing real results.