Beyond Fluid: A Practical Guide to Using Bioimpedance Spectroscopy in Lipoedema

Most clinicians using BIS are trained to look at one number first: the L-Dex. That works well for lymphoedema. 

In lipoedema, patients may present with clear clinical changes such as pain, tissue enlargement and heaviness, yet BIS results may appear “normal.” This creates uncertainty: Is this meaningful? Am I missing something? 

This article focuses on how to use BIS practically and confidently in lipoedema, using a step-by-step approach you can apply in clinic. 

This article is based on a presentation by physical therapist Maureen Macbeth, who shares a practical framework for interpreting BIS results in patients with lipoedema. 

The video below provides the clinical walkthrough, including case-based examples and key interpretation points. The article then expands on the framework as a written reference you can return to in clinic. 

Watch the presentation below before continuing with the article. 

Step 1: Start With the Clinical Picture

Before looking at the SOZO report, clarify the clinical presentation.

Ask yourself:

  • Is the presentation symmetrical or asymmetrical?
  • Is there disproportional fat distribution?
  • Is there pain, particularly in the legs?
  • Is the tissue pitting or non-pitting?
  • What is the patient history?
  • Was onset associated with puberty, pregnancy, menopause or other hormonal changes?
  • Has the condition progressed over time?

These anchor points provide the context for interpreting BIS results.

Clinical Clues 

Symmetrical + painful + fatty tissue + non-pitting 

→ Consider lipoedema 

Asymmetry + fluid signs 

→ Consider lymphatic or vascular involvement 

Clinical rule: 

BIS should support your assessment, not define it. 

The clinical picture should shape everything about how you interpret the SOZO report. 

Step 2: L-Dex Content

Understand what L-Dex is and isn’t measuring in this population. For unilateral oedema BIS results confirm what we see clinically.

  • L-Dex is elevated on one side
  • The segmental analysis shows imbalance
  • Total body water is increased on the side of L-Dex elevation
  • Also, on that side there’s an ECF/ICF imbalance, altered lean soft tissue, reduced phase angle and lower R0

This is BIS performing as expected, all markers pointing the same direction.

Step 3: L-Dex Interpretation

L-Dex remains an important starting point, but in lipoedema it should be interpreted carefully – a normal result does not rule out pathology

You will commonly see:

  • L-Dex within the normal range
  • Minimal side-to-side difference
  • No dominant fluid asymmetry

This does not mean there is no pathology.

If a patient presents with:

  • Bilateral limb enlargement
  • Pain and heaviness
  • Disproportionate fat distribution
  • Non-pitting tissue

and the L-Dex is normal, you are likely dealing with a fat-dominant condition rather than a fluid-dominant one.

The practical takeaway is simple:

Normal BIS numbers do not equal no problem.

This is one of the most important mindset shifts when using BIS in lipoedema.

Step 4: Check Symmetry Using Segmental Data

Once you have reviewed the L-Dex, move to the segmental outputs. Use symmetry patterns to identify emerging lymphatic involvement.

Ask:

  • Are both limbs showing similar patterns?
  • Is the presentation symmetrical?
  • Is asymmetry beginning to emerge?

Interpretation

Symmetrical segmental data

→ Supports the clinical picture of lipoedema

Increasing asymmetry

→ May indicate developing lymphatic or vascular involvement

This is where BIS becomes particularly valuable in lipoedema.

While it may not diagnose the condition itself, it can help identify when fluid-related changes begin to develop on top of existing adipose tissue changes.

Step 5: Look at Trends, Not Single Readings

One measurement in isolation tells you very little.

Instead, track:

  • L-Dex over time
  • Segmental measurements
  • Fluid values across visits
  • Changes in symmetry

Clinical rule:

Trend > Single Number

The most meaningful information often comes from observing how measurements change over months or years rather than focusing on a single result. 

Step 6: Establish a Baseline

To identify change, you need a starting point.

If a baseline exists:

  • Compare current measurements against previous results
  • Look for emerging asymmetry or fluid changes

If no baseline exists:

  • Establish one today
  • Use future measurements for comparison

Many patients present after symptoms have already been present for years.

In these cases, the first BIS assessment becomes the foundation for future monitoring.

You cannot track change without a baseline.

Step 7: Integration – Combine BIS data with clinical examination and patient reported symptoms

The final interpretation should combine:

  • BIS measurements
  • Clinical examination
  • Patient-reported symptoms
  • Longitudinal trends
  • You cannot track change without a baseline.

Quick reference guide

Findings  Interpretation 
Symmetrical limbs + normal L-Dex  Likely lipoedema 
Symmetry maintained + rising L-Dex over time  Emerging fluid involvement 
Asymmetry + elevated L-Dex  Possible lymphoedema or mixed pathology 

The goal is not to make the numbers fit the diagnosis. 

The goal is to determine whether the numbers support, challenge or expand your clinical understanding of the patient in front of you. 

Consider Phase Angle and Body Composition

While not diagnostic, body composition measures may provide additional clinical insight.

Phase angle is of particular interest.

Research has shown that phase angle may decrease with advancing lipoedema stage, reflecting structural changes within adipose tissue including:

  • Adipocyte hypertrophy
  • Macrophage infiltration
  • Progressive fibrosis
  • Reduced cell membrane integrity

These changes can influence bioimpedance measurements independently of fluid accumulation.

A reduced phase angle in the context of an otherwise quiet BIS profile may add biological plausibility to a fat-dominant pathology.

Like all BIS measures, phase angle should be interpreted alongside the clinical picture rather than in isolation.

What a Typical Lipoedema BIS Profile Looks Like

Many patients with lipoedema will demonstrate:

  • Normal or near-normal L-Dex
  • Symmetrical segmental values
  • Higher resistance values
  • Minimal fluid deviation
  • Little evidence of dominant fluid asymmetry

When these findings occur alongside:

  • Bilateral pain
  • Disproportionate fat distribution
  • Non-pitting tissue

they create a coherent picture of a fat-dominant condition.

Case Example

Presentation

A patient presents with:

  • Bilateral lower limb enlargement
  • Pain
  • Soft, non-pitting tissue
  • Disproportionate fat distribution

BIS Findings

  • Normal L-Dex
  • Symmetrical segmental data
  • Elevated resistance
  • Minimal fluid deviation

Interpretation

At first glance, the patient’s symptoms and BIS findings may appear contradictory.

In reality, they are entirely consistent.

The BIS results suggest there is no significant fluid-driven pathology.

The patient’s symptoms are primarily being driven by adipose tissue changes.

The appropriate response is to:

  1. Establish a baseline
  2. Continue monitoring over time
  3. Watch for emerging fluid involvement
  4. Integrate objective findings with clinical assessment

The abnormality is not necessarily in the numbers. It is often found in the mismatch between the numbers and the patient in front of you.

Common Mistakes to Avoid

Avoid these common interpretation errors:

  • Using L-Dex as a standalone diagnostic tool in lipoedema
  • Assuming a normal BIS result means there is no problem
  • Ignoring symmetry patterns in segmental data
  • Overinterpreting a single reading
  • Forgetting that adipose tissue affects impedance differently to fluid

Quick Clinical Checklist

When reviewing a BIS result in a patient with lipoedema, ask:

  • Does this match the clinical presentation?
  • Is the pattern symmetrical?
  • Is there a baseline for comparison?
  • Is there a trend developing?
  • Could this represent mixed pathology?

Conclusion

BIS is not designed to diagnose lipoedema.

However, that does not diminish its value.

Its greatest strengths in lipoedema are:

  • Monitoring change over time
  • Detecting emerging fluid involvement
  • Supporting clinical reasoning with objective data

The most important skill is not reading a number.

It is recognising when the patient’s presentation and the BIS report do not perfectly align—and understanding what that mismatch may be telling you.

When BIS appears quiet but the patient does not, the answer is not to dismiss the symptoms. It is to look more closely, establish a baseline, and continue monitoring with confidence.

Sponsor

Thank you to Impedimed and Regional Health Care Group for sponsoring this article