I have a skinny body but fat arms. Dieting has not helped, what can I do to lose 2-3 cm in my arms?

Without a photograph I cannot comment on your specific issue. However, if you're thin but have unwanted fat in one area such as the arms you probably are an excellent candidate for liposuction.

You really need to see a lipo doc that specializes in lipo for arms, calves and ankles. There aren't many of us who can use the smaller micro cannulas and do the best quality work when it comes to lipo.  All docs do lipo but very few are experts. cost is roughly $4500 on special  and so worth it. sincerely, David Hansen,MD

Your question is a good one but very hard to answer without examining you.  Your options may include liposuction or CoolSculpting or even Brachioplasty, where tissue is surgically removed with or without simultaneous liposuction.  I recommend a consultation with a board certified plastic surgeon for an evaluation of your options.Good luck!