A small MRI study in 16 women reported reduced inner-thigh fat thickness and increased muscle thickness after four HIFEM-plus-RF treatments, with the largest measured changes at three months.
How to interpret the measured result
The inner-thigh anatomy and MRI endpoints belong to this study. They should be interpreted separately from outer-thigh studies and from measures of strength or everyday function.
Study at a glance
Design: Small, uncontrolled MRI study.
Participants: 16 women; three-month MRI n=16.
Research protocol: Four weekly bilateral 30-minute HIFEM+RF treatments.
Follow-up: One and three months.
Evidence visual: Inner-thigh findings at the measured visits
Only observed endpoints are shown. Missing measurements are not estimated.
Fat at follow-up
One month: -22.6 % thickness change; Three months: -27.4 % thickness change.
Approximate absolute reductions: 8.39 mm at one month and 10.12 mm at three months.
Muscle at 3 months
Average muscle measurement: 23.2 % thickness change.
A structural imaging endpoint in 16 women, not a direct strength result.
Circumference
Three-month average: -1.52 cm change.
External circumference, separate from MRI tissue thickness.
Source for the visual: [S07]. Small uncontrolled study in 16 women. No individual shape, strength or result timeline is predicted.
Two tissues, one treatment area
The inner-thigh study examined both the fat layer and the underlying muscle measurements after combined HIFEM and synchronised RF. That is useful because a change in thigh contour can involve more than one structure. [S07]
It is also a reminder that the goal should not be assumed from the treatment area alone. A person may be interested in local contour, while someone else has pain, skin irritation or a functional concern. These are not interchangeable reasons to use a device.
This article explains the imaging study without turning a normal variation in body shape into a medical problem or presenting a particular thigh shape as an outcome everyone should pursue.
For treatment background, read What is EMSCULPT NEO?. This article focuses on the specific research question.
The study design
Duncan enrolled 16 women, with an average age of approximately 47 years. Participants received four weekly, bilateral, 30-minute inner-thigh treatments. MRI was used at baseline and at one- and three-month follow-up to assess fat and muscle thickness. All 16 contributed to the three-month assessment. [S07]
The study was small and did not include a concurrent control group. It offers a specific anatomical observation in the enrolled women, not a universal result for every person, sex, age group or thigh concern.
What changed on MRI?
Average fat thickness was 22.6% lower at one month, corresponding to about 8.39 mm. At three months it was 27.4% lower, or about 10.12 mm. The average muscle-thickness increase at three months was 23.2%. Average thigh circumference was 1.52 cm lower at that visit. [S07]
The largest reported changes were therefore at the later measurement point. The percentages describe group averages in the studied region, not total fat loss or a promised percentage change in the appearance of the entire leg.
Fat thickness, muscle thickness and circumference remain separate results. A single claim that “inner thighs improved by 27%” would discard the detail that makes the study useful.
What the muscle measurement means
The study documented an increase in measured muscle thickness. It did not establish that every participant became a stated percentage stronger, improved balance or recovered from an adductor injury. [S07]
For a person whose concern is function, it is important to ask what will be tested directly. A functional goal deserves an appropriate functional assessment. An MRI contouring result should not be promoted as though it answered every question about muscle performance.
This does not make the imaging irrelevant. It simply gives the finding its correct job: describing a structural observation rather than substituting for all possible clinical outcomes.
Why the three-month review is informative
The inner-thigh data show that the recorded tissue changes differed between one month and three months. They do not establish the exact point at which any individual should notice a visible result. [S07]
A sensible review schedule can use a defined follow-up window while keeping personal expectations flexible. Repeated daily checking is not a substitute for comparable baseline and follow-up documentation.
The study also does not establish a lifelong maintenance schedule. A review should examine what has changed and whether another treatment has a justified purpose. A calendar interval alone is not evidence of need.
What this study does not decide for a patient
Sixteen women cannot represent every possible anatomy, medical history or treatment objective. The study does not define the ideal candidate purely from age or body shape. It also does not show that an individual with a symptom such as pain or swelling should receive the same protocol.
Ask the clinician to explain what is being treated, why the device is being considered and what alternatives are relevant. It is entirely reasonable for the conclusion of an assessment to be that the proposed treatment does not match the main concern.
For appearance-related goals, avoid promises about a “thigh gap” or a fixed silhouette. Neither is a validated endpoint from this research, and neither should be treated as a standard of normality or success.
How ¹EM can use the evidence responsibly
The study is a useful addition to an area-specific evidence library. It means an inner-thigh conversation does not have to rely on abdominal research alone. The anatomical site, treatment course and follow-up period are all explicit. [S07]
For an individual programme, a practical record would distinguish baseline appearance, consistent measurements, the person's goal and the review outcome. Surface imaging may help document the outside of the leg, but it should not be relabelled as the internal MRI test used in the paper.
The key decision is not whether a group average looks attractive. It is whether the measured outcomes are relevant to the person, the potential benefit is worthwhile and the risks and alternatives have been properly discussed.
Safety and source transparency
The report described high comfort and no severe adverse events in its small group. The publication declared no funding or conflicts. Neither statement is equivalent to a guarantee of no risk or an independent audit of all commercial relationships. [S07]
Magnetic stimulation and RF still require device-specific screening, including relevant implants and other medical factors. Unexpected pain or excessive heating should be reported during treatment rather than tolerated as proof of a stronger effect. [G01]
The practical conclusion is encouraging but specific: this study documented inner-thigh fat and muscle changes in 16 women after the studied protocol. Individual suitability and benefit remain clinical questions.
Frequently asked questions
How large was the inner-thigh study?
It enrolled 16 women, and all 16 contributed to the three-month MRI assessment. That is a small clinical cohort, not a result that automatically generalises to every patient. [S07]
What were the main three-month results?
The study reported average fat-thickness reduction of 27.4%, muscle-thickness increase of 23.2% and circumference reduction of 1.52 cm. These are separate group-level measurements. [S07]
Did results differ between one and three months?
Yes. Fat-thickness reduction was about 22.6% at one month and 27.4% at three months. The recorded pattern supports a planned follow-up assessment but does not predict an individual result date. [S07]
Does this study prove increased adductor strength?
It measured muscle thickness rather than a specified percentage change in adductor strength. Functional claims require direct functional evidence and an appropriate individual assessment.
Can I expect a particular gap or silhouette between my thighs?
No. The study does not validate a particular silhouette as an expected outcome. Assessment should focus on a realistic, personally meaningful concern without presenting one body shape as the required standard.
Sources
[S07] Duncan DI. Safety and Efficacy of Simultaneous Application of High-intensity Focused Electromagnetic Field and Synchronized Radiofrequency for Non-invasive Fat Reduction and Muscle Toning in Inner Thighs: Magnetic Resonance Imaging Evaluation. Journal of Clinical and Aesthetic Dermatology. 15(8):28–32. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9436229/
[G01] US Food and Drug Administration. Non-Invasive Body Contouring Technologies. Patient information. 2026. https://www.fda.gov/medical-devices/aesthetic-cosmetic-devices/non-invasive-body-contouring-technologies
Practical information
Start with an individual assessment
General information cannot determine whether treatment is right for you. Request a private assessment with the ¹EM team.
General educational information, not individual medical advice. Published research findings are not ¹EM patient-outcome data. Suitability, experience and results vary.