Lipolytic treatment: how to eliminate localized fat with injectables

The problem: stubborn fat

There are areas that resist even weight loss. The inner knee, flanks, double chin, outer thigh, bra roll, pre-axillary pockets. These are localized fat deposits that have a genetically determined distribution and do not respond proportionally to diet and exercise.

For these specific deposits, there are two major non-surgical tools: cryolipolysis (device-based, controlled cold) and lipolytic injections. This article explains the latter: how they work, what they do, where they are used, and when they should be considered over other options.

What is a lipolytic injection

A lipolytic injection is the intradermal or subcutaneous administration of a chemical compound that destroys adipocytes (fat cells) in the treated area. Once broken, the fat cell releases its contents into the interstitial space, and the lipids are metabolized and eliminated via the lymphatic and hepatic pathways.

The two most commonly used active ingredients in aesthetic medicine are:

• Deoxycholic acid (trade names: Belkyra/Kybella in some countries). It is a bile salt with potent adipocytolytic action. Specifically approved for submental fat (double chin).
• Phosphatidylcholine + deoxycholate (the classic “Lipostabil” formula). A lipolytic combination used in aesthetic medicine for decades in other body areas.

The difference is important. Isolated deoxycholic acid has clear authorization for the double chin and a more defined evidence profile. Formulas with phosphatidylcholine + deoxycholate are used off-label on the body, with extensive clinical experience but different regulatory frameworks.

Mechanism: why it works

When the lipolytic is injected into the subcutaneous tissue plane:

1. Adipocyte lysis: the active ingredient destabilizes the adipocyte membrane, causing it to rupture.
2. Controlled local inflammation: the body activates an inflammatory response that removes cellular debris and released lipids.
3. Moderate local fibrosis: after inflammation, there is some tissue retraction, which helps improve contour.
4. Metabolic elimination: lipids are processed by the liver, just as would happen with any mobilized fat.

Unlike cryolipolysis, which freezes adipocytes (controlled apoptosis by cold), injectable lipolysis chemically breaks them down. The final result is similar: fewer adipocytes in that area.

Indications: where yes, where no

Common areas at Santé:

• Double chin (submental): this is the primary indication for deoxycholic acid. The treatment par excellence for a double chin when there is a fatty component.
• Inner knee.
• Inner thigh.
• Flanks (love handles), lumbar bulge.
• Bra roll (roll that appears on the back).
• Small asymmetries post-cryolipolysis or post-surgical.

Not indicated:

• Global weight loss. This is not a weight-loss treatment; it is for sculpting specific areas in someone with stable weight.
• Visceral fat (intra-abdominal): unreachable and dangerous to attempt.
• Patients with laxity as the main problem: lipolytic treatment can worsen the appearance if there isn't enough fat.
• Pregnancy, lactation, active infection, clotting disorders.

How the treatment is performed

1. Clinical assessment. It is confirmed that the problem is fat, not laxity or edema, and that the amount is reasonable.
2. Marking the treatment area in a grid.
3. Topical anesthesia and/or cold cream.
4. Injection with a fine needle in a grid pattern, into the subcutaneous plane. Calibrated amounts per area.
5. Massage of the area and application of ice.

Duration: 20–40 minutes depending on the area.

Post-treatment: what to expect

The post-treatment period for lipolytic injections is more visible than for other injectable treatments, and it's important to anticipate it:

• Intense swelling in the first 3–5 days. This is the main expected “side effect,” not a complication. It is the inflammatory response that produces the result.
• Sensitivity and mild local pain, manageable with simple oral analgesia.
• Bruising at injection sites.
• Possible erythema and transient nodularity that resolves in 2–3 weeks.

Therefore, we always plan the session away from important events. We recommend not scheduling lipolytic treatments less than 3 weeks before a wedding or event where the treated area will be exposed.

How many sessions and results

Usually 2 to 4 sessions spaced 4–6 weeks apart. The exact number is determined by the fat volume and each patient's response.

Results:

• Visible from the 2nd–3rd session.
• Definitive at 8–12 weeks from the last session.
• Permanent: eliminated adipocytes do not return. But those that remain can hypertrophy if weight is gained. The area will still be proportionally smaller than before, but it is not immune to overall weight gain.

Lipolytics vs cryolipolysis

Criterion	Injectable Lipolysis	Cryolipolysis (CoolSculpting)
Mechanism	Chemical lysis	Apoptosis by cold
Typical sessions	2–4	1–2
Downtime	3–7 days of inflammation	Minimal
Small areas (double chin)	Excellent	Good with specific applicator
Large areas (abdomen)	Less efficient	More efficient
Relative cost	Variable by quantity	Per applicator

Often they are combined: cryolipolysis for large volumes, lipolytics for touch-ups of small areas or residual asymmetries.

Risks to be aware of

• Inflammation, bruising, and sensitivity: expected.
• Transient nodules: infrequent, self-limiting.
• Asymmetries: correctable in successive sessions.
• Damage to noble structures (mandibular nerve in double chin, for example): very infrequent with correct technique. This is why this area is worked on by professionals with anatomical experience.
• Allergic reactions: very rare.

Frequently asked questions

Does it help with weight loss? No. It is for sculpting localized areas in someone with stable weight. If what you need is global weight loss, we talk about other paths: nutrition and, if indicated, GLP-1 with medical supervision.

Is it painful? It is tolerable with topical anesthesia. The first few hours after the session are the most uncomfortable.

Does the fat return? Eliminated adipocytes do not return. If you gain a lot of weight, the remaining ones can grow.

Can I combine it with other body treatments? Yes. It is very compatible with HIFU, INDIBA, mesotherapy, or strength training.

Which area does it work best on? On the double chin, without question. It is the reference treatment for a double chin with a fatty component.

Book your body assessment at Santé

Injectable lipolysis is one more tool within a range of options. The question is not “do I want lipolytics?” but “what do I need?”. Sometimes the answer is lipolytics, sometimes it's cryolipolysis, sometimes it's laxity disguised as fat, sometimes it's clinical nutrition.

Request your body assessment via WhatsApp at +34 699 14 58 87. Avenida Diagonal 384, Barcelona.