Body fat loss for women

by Panos Prokos, MS, CSCS

In this article, I will try to explain the mechanisms behind fat loss and the way such mechanisms make fat loss difficult for women especially in the lower body areas.

Lets begin by a basic introduction to the hormones responsible for fat loss. Actually all of the hormones in the female body are responsible for fat deposition and loss either alone or through their interaction with each other. However, some of these hormones play a more important role than others and these are the ones we are going to discuss here. These hormones are: epinephrine and norepinephrine (also known as adrenaline and noradrenaline respectively), cortisol, estrogens, prolactin, and the thyroid hormones T3 and T4. In this article, I am going to focus on epinephrine and norepinephrine only and leave thyroid hormones, estrogens, prolactin and cortisol to be discussed in another article.

Beginning with epinephrine we should note that it is produced in the adrenal glands which are located on top of each kidney. Norepinephrine on the other hand is produced at the nerve endings of certain cells. Both epinephrine and norepinephrine regulate many functions of the body mainly the sympathetic and parasympathetic nervous system but for the purposes of this article we will be concerned only with their relevance to fat loss. With regards to that, these two hormones affect body temperature, respiration, heart rate and fat distribution.

After the hormones are produced, they are released and circulate in the blood and attach to certain cites located in the human cells called hormone receptors. The cells contain many different types of hormone receptors each one of which sends different messages to the cells. These hormone receptors, which by the way are called adrenoreceptors, are located in many areas of the body such as organs, muscles and most importantly fat cells.

In examining these adrenoreceptors a bit closer we find that there are 4 different types: The alpha-1, alpha-2, beta-1 and beta-2. There is actually a fifth one called beta-3 but we will leave it outside of this discussion.

The fat cells contain the alpha-2 and beta-2 adrenoreceptors. When epinephrine or norepinephrine attach to the alpha-2 receptors on the fat cells, they send a signal to the fat cell to block lipase (an enzyme that breaks down fat), and lock triglycerides within the cell. As a result the fat cells start getting larger and fat begins accumulating. To put it in a very simple way, the alpha-2 receptors are your enemies!!
On the other hand when epinephrine or norepinephrine attach to beta-2 adrenoreceptors, they send a signal to the fat cell to activate lipase, break down fat within the cell and release the triglycerides from the cell. As a result, the fat cell begins to shrink. As you can see, beta-2 receptors are your friends!!

If you have followed me up to this point, you should now get ready for some bad news: Lower body fat cells in women, have very few beta-2 receptors and unfortunately many alpha-2 receptors.

Reading all the above you may be thinking: With all these drugs on the market promising to shed fat here and there, are there any drugs that would activate the beta-2 receptors or even block the alpha-2 receptors? The answer is yes there are!! But getting those drugs to reach the receptors is the second problem. Read on.

The problem with fat cells is that they do not get enough blood. That is the main reason fat has a whitish color instead of red. You see, the little amount of blood that reaches the fat cells gets there through capillaries. The diameter of a capillary ranges from 5 to 20 micrometers. In contrast, the average red blood cell has a diameter of 7 micrometers. So it becomes obvious that we will have great difficulty sending a drug to reach the fat cells. Only a small amount of it will actually make it to the cell.

Finally there is one more problem with using drugs to control fat distribution. Let's assume for a second that we are using a drug that stimulates the beta-1 receptors. We are going to see good results in fat loss in the beginning, however, soon thereafter, the effects start slowing down and eventually we reach a plateau with no further results. At this point, most users either increase the amount of drug or get discouraged and quit taking it altogether. In the first case, they will see some more results which again will soon diminish and stop. In the second case they will realize that as soon as they quit taking the drug the fat starts accumulating back on at an incredible rate. Why is that?
The explanation to this lies in what is known as receptor downregulation. Basically what happens is that the receptors start loosing their sensitivity to respond to the given hormones and can not send a strong enough signal to the fat cell to dissolve fat. At this point some of you may ponder the question: Are there any drugs that can prevent receptor downregulation from happening? The answer is YES, but this discussion is of course outside the scope of this article.

So there you have it. You now know why despite your efforts you still have difficulty getting rid of the lower body fat. I should also mention that drug use for purposes of fat reduction can be extremely dangerous as any drug that stimulates beta-2 receptors also affects vital functions of the body such as heart rate, respiration, etc. So none of them should be used without expert supervision.