Posts Tagged ‘visceral obesity’

Body Fat: Your Biggest and Busiest Endocrine Organ

January 1, 2022

Andrew Siegel MD  1/1/2022 Happy New Year!

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It’s that time of the year when many of us resolve to become better versions of ourselves. One of the top items on the list of New Year’s resolutions is to lose a few pounds and improve our fitness and physical shape.

Sometimes “a cigar is just a cigar,” but at other times a cigar is much more than a cigar.  This is the case with body fat, which is so much more than an inert collection of adipose tissue.  Although adipose tissue is the primary storage site for excess energy (calories), it is also now recognized as an active endocrine organ since it secrete hormones and other chemicals into the blood that have biological actions elsewhere. Within the cells that comprise that layer of body mass located between skin and muscle and surrounding our inner organs there are many ongoing mysterious actions, the topic of today’s entry.

Some fat is good, but not too much

Having some fat on our bodies is a positive attribute, as long as it is not excessive. Fat serves a number of useful purposes: it cushions internal organs; provides insulation to conserve heat; stores energy and fat-soluble vitamins; forms part of the structure of the brain and cell membranes; and is used in the manufacture of certain hormones.

Fat accumulation is determined by the balance between fat synthesis and fat breakdown, an ongoing and dynamic process. Fat synthesis occurs in fatty tissues and the liver and is stimulated by a high carbohydrate diet (glucose inducing insulin release and thus fat synthesis) and fat synthesis is inhibited by fasting (which decreases insulin levels) and prolonged arduous exercise.

The good of fat

If you are carrying excessive pounds you are likely to have less prominent crow’s feet, wrinkles and nasal-labial folds because of the facial deposits of fat cells acting as a filler.  The increased insulation will keep you warmer in the cold winter months and you are more likely to survive hypothermia.  You are more buoyant in water and under starvation conditions you will survive longer because of the larger energy storage. All of that weight bearing will generally result in less bone thinning and less loss of muscle mass that typically accompanies aging.  The cushioning that fat provides promotes better survival in motor vehicle crashes and other forms of trauma and more comfort when sitting on your tailbone or lying on your vertebra.  You likely have a curvaceous, more voluptuous body and many will perceive you to be cuddlier, like a teddy bear.

All fat is not created equal

Not all fat is the same. It is important to distinguish between subcutaneous fat and visceral fat. Subcutaneous fat (“love handles,” “spare tires,” “muffin top”) is fat present between the skin and the abdominal wall.  Visceral fat (“pot belly,” “beer belly”) lies deep within the abdominal cavity and surrounds the internal organs (the viscera).  The nature of the fat is as different as its location.  Although neither type in excess is particularly attractive, subcutaneous fat is inactive and relatively harmless and generally does not contribute to health problems.  On the other hand, visceral fat is much more of a health hazard since its presence increases the risk of heart disease, diabetes and metabolic issues.  It is an abundance of visceral fat that often contributes to a fatty liver.

Subcutaneous fat: unsightly, but not particularly unhealthy. Image from Pixabay.

A beer belly is called a beer belly for good reason as one of the real culprits in visceral fat accumulation is the consumption of liquid carbs, including sodas, iced tea, lemonade, sports drinks, fruit juices, and alcoholic beverages.  Liquid carbs have no fiber and are essentially pre-digested, stimulating a massive insulin surge and rapid storage as fat. It is much healthier to eat the real fruit rather than drink the juice, since the product in its original form is loaded with fiber that fills you up and slows the absorption process and also contains abundant phytonutrients.  You would have to eat 3 oranges to get the same sugar and calorie load as drinking a glass of OJ, and who actually ever eats 3 oranges in one sitting?

Visceral fat: unsightly and hazardous to your health. Image by Pixabay

The bad of fat

Fat is an active endocrine (hormonal) organ that for many people is the largest endocrine organ in the body.  A moderate amount of body fat helps to provide us with a nice contour and shape, but in excess does way more than just create an unsightly appearance.

Fat produces numerous hormones and other chemical mediators that can have detrimental effects on all systems of our body. The more body fat, the greater the potential detrimental effects. Obesity is characterized by increases in fat cell number, fat cell size, or a combination of the two and can be thought of as a state of systemic, chronic, low-grade inflammation because of the bioactivity of the fat cells.

In other words, fat is not just an inert collection of adipose tissue, but a metabolically dynamic organ consisting of fat cells capable of manufacturing and secreting numerous biologically active compounds that regulate metabolism.  Some of these bioactive substances include hormones, growth factors, enzymes, cytokines, complement factors, and matrix proteins. These bioactive substances are released into the bloodstream and have metabolic and physiological effects on remote target tissues. These substances include adiponectin, leptin, aromatase, angiotensinogen, resistin, visfatin, acylation stimulating protein, sex steroids, glucocorticoids, tumor necrosis factor, interleukin-6, plasminogen activator factor, vascular endothelial growth factor, insulin-like growth factor, among others. See chart below:

Chart from: Biochemistry of adipose tissue: an endocrine organ, Marisa Coelho, Teresa Oliveira, Ruben Fernandes, Arch Med Sci 2013;9, 2: 191-200

Although both subcutaneous and visceral fat are both metabolically active, visceral fat is the more active and thus the more potentially harmful of the fat subtypes.  In my opinion, visceral fat ought to have a specific name, as do other endocrine organs (e.g., thyroid gland, adrenal gland, pituitary gland, etc.). This name should convey the potentially dangerous nature of this “gland.”  I suggest “die-roid,” as a takeoff on the thyroid gland, because of its potential for inducing dire metabolic repercussions, including the risks of metabolic syndrome, diabetes, hyperlipidemia, hypertension, atherosclerosis, heart disease and premature morbidity and mortality.


One of the active hormones present in visceral fat is aromatase, which functions to convert testosterone to estrogen.  This leads to lower testosterone levels that further induces visceral fat accumulation and higher levels of estrogen. This typically results in a larger belly and man breasts, as well as decreased libido, erectile dysfunction, and penile shrinkage.  Even more importantly, the insulin resistance that often results can induce dyslipidemia (high triglycerides, low HDL, high LDL cholesterol) and increased cardiovascular risk, contributing to coronary artery disease, hypertension, diabetes, and possible stroke.

The Good News

The good news about visceral fat is that the very metabolic activity that makes it so potentially dangerous also makes it relatively easy to lose with appropriate lifestyle modification.  This is as opposed to subcutaneous fat, which is tenacious and can be extremely difficult to lose.

Wishing you the best of health and a happy New Year,

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Dr. Andrew Siegel is a physician and urological surgeon who is board-certified in urology as well as in female pelvic medicine and reconstructive surgery.  He is an Assistant Clinical Professor of Surgery at the Rutgers-New Jersey Medical School and is a Castle Connolly Top Doctor New York Metro AreaInside Jersey Top Doctor and Inside Jersey Top Doctor for Women’s Health. His mission is to “bridge the gap” between the public and the medical community. He is a urologist at New Jersey Urology, the largest urology practice in the United States.  He is the co-founder of PelvicRx and Private Gym.  His latest book is Prostate Cancer 20/20: A Practical Guide to Understanding Management Options for Patients and Their Families. 

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Video trailer for Prostate Cancer 20/20

Preview of Prostate Cancer 20/20

Andrew Siegel MD Amazon author page

PROSTATE CANCER 20/20 is now available at Audible, iTunes and Amazon as an audiobook read by the author (just over 6 hours). 

Dr. Siegel’s other books:

THE KEGEL FIX: Recharging Female Pelvic, Sexual, and Urinary Health


MALE PELVIC FITNESS: Optimizing Sexual and Urinary Health

PROMISCUOUS EATING— Understanding and Ending Our Self-Destructive Relationship with Food

FINDING YOUR OWN FOUNTAIN OF YOUTH: The Essential Guide to Maximizing Health, Wellness, Fitness and Longevity