Does Fat X Core Really Work? Expectations and Limitations Revealed by Research on the Abdomen and Upper Arms

Injections of deoxycholic acid such as Fat X Core have reports of fat reduction in the abdomen and upper arms, but research is predominantly small-scale, and the basis for recommending it is considered weak[1]. In the United States, approval is limited to use under the chin; use on the body is off-label.[2]. How much fat is reduced depends on the injection site, dose, and number of treatments.[3][4].

How much reduction occurs in the abdomen and upper arms?

There are reports of reduction, but a definitive answer is not yet available. Among 11 studies examining use in various body locations, success rates exceeded 85% at evaluation 1–21 months after treatment.[1].

However, due to the scarcity of high-quality studies, the basis for recommending off-label use is considered weak.[1]Studies injecting into the flanks also exist, but involved small numbers of participants, and the authors themselves note that results are difficult to generalize.[2].

Does effectiveness differ by location?

Differences appear to exist. A report using 1269 participants with a slightly different injection formulation (combined with phosphatidylcholine) showed good efficacy in the face and upper arms, and average efficacy in the thighs and around the knees.[3].

In this report, an average of 4 injections were given at 4-week intervals, with the largest change appearing after the first injection.[3]This was a retrospective review from a single facility, and it should be noted that the formulation differs from Fat X Core.[3].

What happens in the body?

In the injected fat layer, fat cells break down and diminish. In a 14-person study performed before abdominal surgery, changes were confined to the subcutaneous fat layer, and were more pronounced with higher drug concentration.[5].

Inflammation was strong immediately after injection and had largely subsided by day 28.[5]Swelling tends to occur for some time after injection, and changes should be assessed afterward.

How does it differ from the approved under-chin drug?

While there are large trials for under-chin use, research on body use is insufficient. In trials of the approved under-chin drug, 58.8–63.8% of people showed at least one-stage reduction in fat, exceeding 28.6% with placebo.[6].

Use over a wide body area has not yet been sufficiently studied, as indicated.[7]Even in under-chin trials, all were reported to involve pharmaceutical company involvement.[8].

How do side effects relate to dose?

Most are mild reactions at the injection site, but heavier side effects are reported to occur more readily with higher doses.[4]When injecting into the body, the treatment area tends to be wider, so confirm the dose being injected per session.

In flank studies, skin necrosis occurred at one injection site, considered to result from placement in the superficial skin layer.[2]Side effects listed for the approved drug include skin erosion, nerve numbness, and infection.[7].

How should expectations be set? Assessment guidelines

Fat X Core, being a method with limited research, is most realistic when expectations are kept modest.[1]Confirming the following points before treatment will make decision-making easier.

Location: Is it a site with research, such as the upper arms or flanks?[1][3]

Dose: The amount injected per session and width of treatment area[4]

Number of sessions: How many visits, and how much change to expect after the first session[3]

Side effects: Are safeguards in place against skin necrosis or erosion?[2][7]

Research limitations: Will the provider explain that this is off-label use?[1][2]

Whether the fat of concern can be reduced by injection, or whether another method such as liposuction is more suitable, cannot be determined by article alone. During consultation, have the fat thickness and skin laxity assessed, and decide the treatment area and number of sessions together.