Would it help to wear a faja or compression garment 4 month after abdomen lipo to help retract the skin? If so, for how long?

A compressive garment primarily provides comfort after liposuction. It's long-term benefits are doubtful relative to the final outcome. Loose skin will have to be addressed separately.

I have my liposuction patients wear a compression garment (faja) covering all treated 24/7 except to shower for 4 weeks post op. This helps ontrol swelling as the compression on your tissues helps your body to reabsorb the edema fluid that accumulates in the tissues after any procedure. This can take quite some time to happen without help from the compression garments. It also helps improve contour. Compression helps to keep the tissues adherent to the underlying structures while healing, this can help prevent the wrinkled skin appearance that can happen when the tissues heal in ways we don't want them to.

A compression garment is used to support and provide compression to the area after liposuction. It is usually recommended to be worn for 4-6 weeks, post the procedure. It would not help to use one 4 months after liposuction.

After 4 months following VASER liposuction you are at an END point in healing & skin retraction. Sorry. Best to seek in person second opinions for other modalities to hep achieve tighter abdominal skin, i.e.: ThermiTight RF 250 sessions (4 to 6 sessions @25 minutes each with a per session costs of $700 or $2,800 Total fees) or a mini TT, to Full Skin only TT.