Entity Last reviewed 2026-07-07

What Is HIFEM (High-Intensity Focused Electromagnetic Field)?

HIFEM is an energy-based technology — used in devices like Emsculpt — that delivers focused electromagnetic pulses into a targeted muscle group to induce rapid, involuntary contractions. It’s marketed and clinically studied for muscle toning and strengthening, typically in four 30-minute sessions over about two weeks, with a secondary fat-reduction effect in the treated area.

How it works

HIFEM technology is “intended for muscle toning, firming, and strengthening” by inducing contractions through an externally applied electromagnetic field rather than voluntary effort (Katz et al. 2019). Kinney & Lozanova’s MRI study describes treatment as four abdominal sessions, spaced 2–5 days apart, 30 minutes each, and states the device “induce[s] almost 20 thousand pulses in one 30-minute session,” a frequency of nerve stimulation that “leads to supramaximal muscle contractions which are not achievable voluntarily” (Kinney & Lozanova 2019, Discussion).

Who shouldn’t use it

The clinical study behind this page’s effect-size data excluded pregnant or breastfeeding patients, anyone with a heart disorder, and — more broadly — “any medical condition contraindicating the application of an electromagnetic field” (Kinney & Lozanova 2019). That general clause is why providers also screen for pacemakers and other electronic/metal implants, though the study doesn’t name those devices individually.

What the evidence shows

An MRI-based study of 22 patients found four HIFEM sessions produced an average 15.4% increase in rectus abdominis muscle thickness, an 18.6% reduction in adipose tissue thickness, and a 10.4% narrowing of rectus diastasis, all statistically significant at 2 months post-treatment (Kinney & Lozanova 2019). A separate abstract-only ultrasound study of 33 patients reported abdominal fat-layer reductions of 19.0% at one month and 23.3% at three months (Katz et al. 2019).

Where it’s used

HIFEM is the mechanism behind Emsculpt; the newer Emsculpt Neo combines it with simultaneous radiofrequency heating for a larger fat-reduction effect (see Emsculpt Neo vs Emsculpt: What the Added Radiofrequency Actually Changes).

Sources