Unintentional fat loss from hifu/radio frequency - does this happen in the forehead area where there is already low fat?

This usually happens when the treatment is done too aggressively. Meaning, too deep, too much heat, etc.

High-intensity focused ultrasound (HIFU) and radiofrequency devices work by delivering heat into deeper tissue layers. At certain depths, that heat can tighten skin and stimulate collagen, but it may also affect fat cells — which is why some patients report volume loss in areas like the cheeks or under the eyes.

In the forehead, there’s already very little fat. Most of what you’re treating is skin and underlying muscle, so significant fat loss there is unlikely. The main risk would be skin or tissue injury if the energy is placed too deep or too aggressively.

In the neck, mild fat reduction can sometimes be a benefit, but again, the primary goal of these treatments is skin tightening, not fat melting. The effect really depends on the device used, the settings, and the skill of the provider.

Bottom line: HIFU and RF are generally safe when performed by an experienced practitioner, but unintentional fat loss is a possibility in fat-rich areas of the face. Careful treatment planning helps minimize that risk.

Radiofrequency uses heat energy to tighten skin. It can also create targeted fat loss. The amount of fat loss is influenced by the depth and strength of the heat energy used. This is why it is important to select an experienced provider for your treatments. I've included a video on Morpheus8 which combines RF technology with microneedling that I hope you find helpful.