David B. Reath, MD
Knoxville, TN (865) 450-9253

Your Body Fat: An Expert Guide

The majority of my plastic surgery practice here in Knoxville is body contouring surgery, which is changing the shape of my patient’s bodies. Inevitably this means dealing with fat. We all have it. We all need it. Some have less than they want; most of us have more than we want. Frequently we get questions about getting rid of excess fat, and there are many misconceptions about this. So, I thought it might be a good idea to talk about it.

Where Your Fat Is

While your first thought might be everywhere, it’s not so simple. Fat is contained in fat cells or adipocytes. The number and location of cells we have are determined by several factors, including our genetic makeup, level of fitness, and so on. But genetics is key here. More about this later.

The number of fat cells we have is pretty much fixed after we have gone through puberty. These cells are storage cells for the excess caloric energy we have consumed. If we burn more calories than we eat, the fat cells get smaller. If we eat more than we burn, they get bigger. The key thing is that the number of fat cells we have doesn’t change.

If we are born with areas of our bodies that are out of proportion to the rest of the body, they have more fat cells. No matter what our level of fitness is, these areas will always be out of proportion. That’s where liposuction and/or CoolSculpting comes in. They both remove fat cells, and these cells are gone for good. This allows these areas to be more in proportion with the rest of the body.

Two Types of Fat: Subcutaneous and Visceral

subcutaneous fat vs visceral fat
Generally speaking, we can think of fat as two different types depending upon where they exist in our bodies. Everyone has both subcutaneous fat and visceral fat. Subcutaneous fat exists in the layer between our skin and the underlying muscles. (The image on the left) I can remove it through surgical excision in a tummy tuck or body lift. Or it can be removed by liposuction or CoolSculpting. So, it is this layer of fat that we can alter with plastic surgery.

Visceral fat is the more difficult entity. (The image on the right) It is internal fat that exists primarily in our abdomens around our internal organs. The proportion of our body fat that is visceral is genetically determined, which is very unfair for those who have this body type. Surgically, this cannot be altered. Weight loss alone is the only method of reducing this.

I see many patients who have what is known as an endomorphic build. These folks have a large amount of visceral fat and a relatively small amount of subcutaneous fat. Their abdomens are round and full, but their arms and legs are relatively skinny.  Plastic surgery is not likely to give them the results they want, only weight reduction can provide real improvement. Sad, but true.

Why Plastic Surgery Won’t Work For Weight-Loss

Let me start with the difficult topic of obesity. There are many misconceptions about the surgical removal of fat and its effect on our body weight or Body Mass Index (BMI, which is a function of our height and weight). Plastic surgery is not weight loss surgery; it’s surgery to change the shape of the body.

Body Mass Index Illustration

When evaluating someone for surgery, I always consider their current BMI. Clinically, obesity is defined as a BMI greater than 30. Many who are significantly overweight want to know why I can’t just suck all the fat out with liposuction. My first response is that I would if I could.

There is a limit to the amount of fat that liposuction can remove safely and as an outpatient procedure. This is limited by blood loss and fluid shifts in the body after surgery. Usually, this is about 3 liters which equates to a little over 6.5 pounds. So, not so good for weight reduction.

The other question I often get is why I won’t do an operation like a tummy tuck on significantly overweight people, particularly if the most problematic area for them is the abdomen. Why not just cut it all off, right? Well, not so simple.

Obesity in and of itself is a risk factor for surgery. The higher the BMI, the greater the risk of surgical complications such as infection, non-healing, deep vein thrombosis or pulmonary embolism, prolonged recovery, and hospitalization. This type of surgery is totally elective. There is no reason to undertake elective surgery at an increased risk, especially if this risk factor can be improved.

So let me zoom in on the subcutaneous fat layer itself. Obviously, this is thicker in heavier patients. I know, duh.

The fat layer is the least vascularized layer of our body. Fat cells don’t need as much blood supply, so fewer blood vessels are in this layer. This affects the healing of this layer and recovery in general.

Healing requires optimal blood supply to deliver oxygen to the tissues that are healing. If there is insufficient blood supply, the wounds will not heal (this is also true in smokers). The tissue at the edges of the incision can die (know as necrosis), the wounds can open up, and infection can set in. This creates a real mess. Such wounds in areas of increased fat can take months to heal. Open wounds and delayed healing can lead to an increased disability, time off from work and everyday activities, more complex wound care, or even hospitalization.

This is not a place I want to go with my patients, and why I require my patients’ BMI to be about 30 or less before surgery. However, there is one exception to this. If someone has a large muscle mass (as in weight lifters or other athletes), they may be good candidates at a higher BMI because it is the muscle and not fat that elevates their BMI.

If a patient is really fighting with obesity and has not been able to deal with it through diet and exercise, bariatric surgery may be the best option, not plastic surgery.

Let’s Talk About Adding Fat.

Adding fat to our bodies, which is known as fat grafting, is a topic of great interest to plastic surgeons. Fat grafting involves removing fat from one area through liposuction, separating the fat cells from the liposuction aspirate, and injecting the fat elsewhere, usually in the face, breasts or buttocks.

When such fat is injected into the body, it needs to be revascularized to survive. The blood vessels or capillaries in the grafted area need to grow into these fat cells to deliver oxygen and allow them to live. The better the blood supply in the area being grafted, the better the outcome. Also, smaller amounts of fat require less ingrowth of the capillaries.

Perhaps the most successful area for fat grafting is in the face. Endogenously the face has a very robust blood supply. Further, the amount of fat to be grafted is relatively small, usually only a couple of cc’s per area. So the smaller amount of fat in a well-vascularized area will have a better chance of “taking” or surviving.

Fat grafting to the breast is also an area of interest. Let me start by saying that the surgeons who have the most experience with this have the best results. I am not one of these surgeons. It can be an involved process, sometimes involving stretching of the breast before fat grafting. Then there is a finite volume of fat that can be grafted at any one time. Again, this has to do with the fat injected to allow optimal revascularization and graft survival. If someone wants to go up a cup size or slightly more, this can work. But if someone is looking to go from an A cup to a C or D cup, breast implants are the best option. It may be possible to get there with fat grafting, but it will take numerous operations and be much more costly.

The Brazilian Butt Lift or BBL

Recently fat grafting in the buttock (aka, the Brazilian Butt Lift) has come under significant scrutiny due to safety concerns. To ensure the best fat graft survival, surgeons injected the fat into the buttock musculature because of its robust blood supply. Such blood supply means large blood vessels are going to (arteries), and from (veins), these muscles. Usually, the grafting to buttock involved a large amount of fat to achieve the desired result. If some of this fat is injected into a large vein, it can travel directly to the heart and lungs. The results are uniformly disastrous, leading to instant death in many cases. You can read more about this in the post, Buttock fat grafting is an operation I will never perform.

The Fat Wrap-Up

Fat is an essential part of our bodies. We need it for warmth and insulation. We need it to store energy. We need it in the right areas to look our best. Fat is not bad. However, too much of a good thing… As a plastic surgeon, it is essential to know which fat I can manipulate through surgery, how much I can do, and who is the right person to operate on.

All the best,

Dr David B. Reath blog signature

 

 

David B. Reath, MD

 

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