How is Body Fat Accurately / Concretely Measured Before Suctioning It out Through Liposuction?

It is actually simpler than you think. Just pinch the skin and measure the difference between your index and thumb. That distance is a double layer of fat under the skin. 2 people can have the same BMI but one has more fat in the love handles and the other has more in the lower abdomen. The only way to know where to remove the fat from and how much to remove is to examine the patient.

I hope you realize that this format of posting questions and receiving answers lacks the face to face direct communication required for you to make an informed decision regarding your surgery.

My response to your question/post does not represent formal medical advice or constitute a doctor patient relationship. You need to consult with i.e. personally see a board certified plastic surgeon in order to receive a formal evaluation and develop a doctor patient relationship in order to know if this assessment is valid.

Determining the amount of body fat to remove is based on many factors that are determined at the time of consultation.  A physical exam will help determine amount of fat versus skin and muscle as well as the location of the fat.  An accurate amount of fat to remove is not as important as improving the contour of the treated area.  There is finesse and art to liposuction that comes with experience.

      There is not a compelling need to know the body fat percentage prior to liposuction as liposuction is used to target stubborn areas not for overall fat reduction.  The relative volume to be removed from an area is less important than achieving contour improvement.  Find a plastic surgeon with ELITE credentials who performs hundreds of liposuction procedures each year.  Then look at the plastic surgeon's website before and after photo galleries to get a sense of who can deliver the results.  Kenneth Hughes, MD Los Angeles, CA

The determination of how much body fat there is, as opposed to muscle and skin, is made on physical exam. Liposuction is not about a "concrete measurement" or number. It is a technique used to contour the body and remove focal unwanted fat deposits. The amount of fat that can be removed safely is not always the amount you want to remove. What you leave behind in liposuction is more important than what you take out. You want your plastic surgeon to take the right amount of fat from the right locations, leaving a nice contour. Taking as much as possible does not equal the best result. The amount and quality of the skin in those areas is important too, since once the volume is removed, you are relying on the skin to shrink down around the smaller volume. If you have excess skin, or poor quality skin, you may need excision of the skin for the best result.

The determination is made by physical examination and experience. Fat can be felt throught the skin. Certain areas do not normally store extra fat, and can be used as a benchmark for skin thinkness. Other areas, that tend to store fat disporportionately, can be compared to the "normal" skin thickness with a pinch test. Experience allows me to make an educated guess about how much "extra" fat there is, and how much can be removed. With liposuction, proportions are more important than absolute volume.  Liposuction is not a weight loss tool, but a way to sculpt the body by removing localized, disproportionate accumulations of fat.

Actually, when it comes to liposuction, there is no exact calculation.

The most important thing is the doctors skill as a surgeon and a listener.

The doctor must really listen to what the patient goals are, and then be sure that that they can be achieved.

Secondly, liposuction works by removing fat, but the skin must be able to re-drape or shrink to the smaller sized person (thus the doctor must carefully assess this pre-operatively, and balance amount removed vs. ability of skin to re-drape).  On top of that, the surgeon must think three dimensionally so that the final shape looks good and there are no significant surface irregularities.

Regarding BMI, lipo is not a weight loss procedure, so that is not really a consideration.

When it comes to the result, really it comes down to the surgeon's skill anad experience.

There is no accurate method available to predetermine exactly how much fat will be removed from each target area.

An experienced plastic surgeon makes an estimation based on the evaluation of the patient. The total amout  removed has a safe limit and the amount removed safely from  each are is a clinical judgement by the surgeon during surgery.

One of the most reliable, simple, and direct  methods for analyzing body composition is  based on the bioelectric impedance, which involves measuring of  the resistance to electrical current applied through  electrodes, the resistance is inversely  proportional to  total body water which travels through the stream.
Muscles, blood vessels and bones are body tissues having a high water content which conducts electricity easily, body fat is tissue that has little electric conductivity, the Body Fat Analyzer sends an extremely weak electrical current to the body to determine the amount of fat tissue, weak electrical current is not felt while operating the Body Fat Analyzer. The body fat percentage is calculated by a formula that includes five factors: electric resistance, height, weight, age and gender.
At present there are several brands that offer household equipment to calculate the weight and percentage of body fat fairly reliable, a couple of examples: the balance fat monitor Omron HBF-400 Inner Scan and balance BC551 Tanita
Physical examination can not accurately measure the amount of fat that can be removed in an  determined  anatomical area , but based on the body mass index, the thickness of the skin (as determined by pinch test) and the surgeon's experience can give a fairly close idea , however, I should clarify that liposuction is not a weight loss procedure but to shape and contour the figure.
The most important factor to consider is not only  the total volume of extracted fat but also  the  fat that is left  in the different areas to maintain harmony. If you want to  know which is  the maximum amount  of fat that can be  securely removed in a certain area I can tell you that the reference  is until  the skin and subcutaneous tissue has a thickness of 0.5 to 1 cm depending on the area (when  thickness of skin is lower , skin damage may ocurrs by affecting the blood supply.)
The  total volume of fat that can be extracted will depend on hemoglobin levels before surgery, medical history ( health condition ) and the amount of bleeding during the procedure, I have had cases where I have been able to extract up to 11 liters of fat without the need for transfusion and with excellent results. As a rule when extracted more than 5 liters of fat (mega liposuction) increase the risk of bleeding and need for transfusion as well as the risk of  complications.
However, in the medical reports are very few cases that have had disastrous results. As calculated, the possibility of a fatal outcome is 1 person between 5000 (ie 0.02%), which implies a reduced risk. In any case, it is best to always be in the hands of physicians with recognized expertise and prestige.

Fat amounts are estimated, not somehow measured, before liposuction.  There is no concrete way to know exactly how much fatty tissue is in a given area, but a plastic surgeon can have a guess from experience, and the look and feel of the area, your height and weight, and so on. There is no set amount from a single area that is dangerous, but the overall amount of all the areas being treated.

The only reason a doctor might want to estimate the amount is so safety limits are not exceeded. For example a surgeon would not like to try to suck out 10# of fat from an individual in one sitting.

Liposuction is not a weight loss technique, it is a body contouring technique, of course.  As long as safety limits are not exceeded, the estimates of fatty tissue volume are not particularly important.

The only way to adequately quantify body fat is through use of MRI and complex calculations, which would be financially unfeasible for most people.  Also, since the amount of fat removed is still determined artistically, the exact amount would still be an estimate.  Most experienced plastic surgeons are good at making this estimate at the time of physical exam without a lot of costly imaging.