Obesity is a disease state, a condition related to poor health. Weight problems in the epidemic proportions being reported in the U.S. and other developed countries is a fairly recent phenomenon, brought on in part by less physical occupations, more sedentary recreation and easy access to food with larger portions the norm.1,2
For centuries, fat people were felt to be lazy or overly indulgent. Sir Thomas Aquinas listed sloth as one of the seven deadly sins. Director David Fincher portrayed the victim of sloth in the noir film “Seven” as a morbidly obese man forced to kill himself by eating canned spaghetti until his stomach burst. Heavy people excuse their condition by blaming a thyroid condition, big bones or baby weight following a pregnancy.
During the last few decades, it has been discovered that there are a number of genetic and metabolic factors that may make one more prone to becoming overweight or obese; some obese individuals are leptin-resistant or insulin-resistant, have melanocortin receptor mutations or gherlin imbalances, etc.3 The number of people with actual genetic causes for weight problems is a small percentage of the obese, however. Unfortunately, the knowledge of factors predisposing a few to obesity provides varied and exotic options for excuses to the many unaffected – but still obese – majority. Lifestyle remains the primary cause of obesity for most.2
Though it’s not yet fully understood how obesity develops, it’s clear that a number of factors are involved. Perhaps just as important, it’s becoming clear that obesity increases the risk of a number of different disease states, including cardiovascular disease, certain cancers, diabetes and hypertension, among others.4
Body Mass Index: A Has-Been?
As a majority of Americans are now either overweight or obese, and heart attacks remain the leading killer of men, it’s essential for the connection between weight problems and cardiovascular disease to be understood and communicated to the public. Older readers may remember the insurance tables listing “ideal bodyweight” by height.5 By today’s standards, those weights seem inappropriately light, especially for athletes. For example, the ideal bodyweight for a 6-foot-tall man has been listed at 157-170 pounds, and that’s with wearing 5 pounds of clothes. In comparison, some 6-foot-tall celebrities weigh between 200 and 220 pounds.6
In the hopes of improving the predictive power of bodyweight on future disease risks, experts included algebraic functions to create the body mass index (BMI). BMI is calculated by dividing weight in kilograms by the square of height in meters. So, for those who use the metric system regularly, it’s only slightly complicated. Using pounds, feet and inches makes the formula overly complex. Fortunately, tables have been published allowing people to determine their BMI more easily. Numerous studies have been published correlating health status and BMI. Having a BMI of 25 categorizes a person as being overweight, whereas a BMI of 30 registers as obese.
As scientific as the BMI seems, a large number of studies have shown that it’s no better than simply measuring the waist circumference (waistline) and in many cases, it’s not even as good.7-16 For men, it was learned that a waist circumference of 89 (overweight) and 101 (obese) centimeters was more predictive of cardiovascular disease-related risk factors than a BMI of 25 and 30.10,17 Translating these numbers into the more common and useful English system, waist circumferences of 36 and 40 are indicators of weight- and fat- related metabolic disorders and cardiovascular risks.
This is actually a major step forward in that the public is now provided with a simple and convenient measure to use in self-monitoring and seeking treatment. Very few people will take the time to calculate BMI, and the height-weight tables are insensitive to changes in lean body mass, including muscle.
Waist circumference appears to be better than skinfold measurement, not just because of its ease of use, but because of the type of fat it measures.18 Skinfold measures subcutaneous body fat, the fat that lies immediately under the skin. Subcutaneous fat is not homogenous, as it contains two distinct types of fat. The topmost layer, or superficial subcutaneous fat, appears to function as an insulating layer helping to preserve body heat. The deeper layer of subcutaneous fat is more metabolically active, releasing or storing fat according to the body’s needs. Fat released from the deep subcutaneous fat layer enters the general bloodstream and is available to all tissues equally.19,20
There’s More to Fat Than Meets the Eye
In contrast, there are other distinct fat masses contained within the abdominal cavity, basically between the ribs and pelvic bones, lying beneath the abdominal muscles. This fat is collectively referred to as visceral fat, including extraperitoneal and intraperitoneal fat. Extraperitoneal fat surrounds the kidneys and adrenal glands, protecting them from trauma. Intraperitoneal fat is the most important category of body fat, speaking from a metabolic perspective. Intraperitoneal fat surrounds or covers the intestines.
Intraperitoneal fat has many differences from subcutaneous fat. It more readily stores or releases fat, and the released fat travels directly to the liver rather than being diluted in the entire bloodstream.4 In addition to fatty acids, intraperitoneal fat releases a number of active hormones and hormone-like chemicals. These hormones cause a myriad of biological changes, many of which are associated with an increased risk of cardiovascular disease, diabetes, hypertension, cholesterol problems, etc.
Though it appears intraperitoneal fat is the most vital compartment to measure, it’s difficult to directly assess it, as it lies under the abdominal muscles. CT scans and MRI can visualize and measure intraperitoneal fat, but it’s a very expensive, time consuming and not a widely accepted method. Fortunately, a simple tape measure can provide a close approximation of intraperitoneal fat stores.21
Scientists have demonstrated a clear association between waist size and health risks, but only recently have they begun to explain exactly how an excess of intraperitoneal fat may cause some of the metabolic diseases associated with obesity.4,22 The longest held understanding involves blood flow. As mentioned previously, the blood supply of intraperitoneal fat drains directly into the liver. As the intraperitoneal fat mass increases, so, too, does the rate of fat release. In other words, the more fat there is, the more fatty acids that are released into the bloodstream. When the liver is subjected to high levels of fats, it releases more blood sugar and does not break down insulin as well.4,22-25 Also, more LDL (bad cholesterol) is released and the LDL particles are smaller, which is a more dangerous form.26
This effect on the liver explains in part the predisposition to diabetes and glucose intolerance, as well as higher rates of atherosclerosis (a form of cardiovascular disease). Fats released into the general bloodstream may also have a negative impact. When muscle is exposed to high fatty acid levels, it burns more fat for energy. This shift to fat oxidation decreases the use of, and need for, sugar (glucose).27 Muscle is one of the major glucose disposal sites, so when glucose uptake is decreased, insulin resistance sets in – one of the factors in the metabolic syndrome.
Obesity is associated with other factors relating to health risks. Inflammatory markers, such as C-reactive protein, are elevated in obesity.28 HDL (good cholesterol) is lower when intraperitoneal fat stores are enlarged, and the HDL particle size is reduced – a dangerous trend.29 Triglyceride levels, fats that travel in the bloodstream, are also elevated.30 High triglycerides are associated with many conditions, most importantly cardiovascular disease.
Fat Cells are Not Just Storage Sites
Scientists have begun to realize that fat cells are not simply passive cells storing fat, but that they serve an endocrine function – releasing hormones and chemicals that affect the rest of the body’s metabolism. Several factors have been closely studied, revealing that increasing intraperitoneal fat may result in changes that increase the risk of diabetes, cardiovascular disease and hypertension.
When fat is stored preferentially as intraperitoneal fat, as opposed to subcutaneous fat, leptin levels are low relative to the amount of body fat. Low relative leptin levels reduce insulin sensitivity, predisposing one to diabetes and glucose intolerance.4 Intraperitoneal fat produces plasminogen activator inhibitor-1 (PAI-1), which prevents the breakdown of clots arising in the bloodstream.31 High PAI-1 levels associated with intraperitoneal fat increase the risk of clots (thrombi) blocking blood flow to tissues such as the heart and brain, resulting in heart attacks and strokes.
Adiponectin is a protective factor produced by fat cells. However, adiponectin levels are decreased in people with elevated intraperitoneal fat mass, removing the protection against insulin resistance and cardiovascular disease.32 Interleukin-6 (IL-6) may be produced to a greater degree by intraperitoneal fat.4 A dangerous chemical messenger, IL-6 increases insulin resistance and blood triglycerides. This is also the case with tumor necrosis factor-α, a related chemical messenger.4
Lastly, angiotensin is a hormone involved in regulating blood pressure.33 Angiotensin and a related enzyme are produced in fat cells, and in excess, may cause hypertension. These factors and over 100 others are produced by fat cells. The realizations that fat cells are not passive storage sites, but instead behave as an endocrine organ, provide a solid basis for explaining the metabolic consequences of obesity.
Taking Action
Most cultures instinctively hold obesity in low regard, viewing such individuals as less healthy than their active counterparts. A greater understanding of physiology has removed the stigma of obesity as an indication of spiritual bearing or a personality trait. In addition to lifestyle changes, metabolic and genetic factors play a role in the predisposition to obesity. Regardless of the cause, the presence of excess fat is associated with increased health risks and is reason to return to a healthy weight.
The manner in which fat is distributed affects the risks to a degree, with central fat (or a beer belly) being much more hazardous in comparison to underarm chicken fat and cellulite presentation common to women. Central fat, also called visceral fat, contains intraperitoneal fat, which surrounds and covers the intestines. The blood supply of this fat drains directly into the liver, negatively affecting cholesterol and sugar control. Fat releases hormones, just as other endocrine organs do, affecting the metabolism of the entire body. Cumulatively, these changes create a markedly increased risk when central fat causes the waistline to exceed 90 and 100 centimeters (approximately 36 and 40 inches).17
Take time to wrap a tape measure around your waist. If your waistline is nearing 36 inches, consider changing your diet and training to drop a couple of inches. If your waistline exceeds 40 inches, walk carefully to the phone and immediately call someone who can assist you in losing six inches off the belly. If living the later years of your life in good health is important to you, this simple advice may allow you to add a few years and avoid the fragility and decrepitude of old age.34
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