What is Obesity

Obesity is one of the most pervaise, chronic diseases in need of new strategies for medical treatment and prevention. As a leading cause of United States mortality, morbidity, disability, healthcare utilization and healthcare costs, the high prevalence of obesity continues to strain the United States healthcare system.
 

Obesity is defined as excess adipose tissue. There are several different methods for determining excess adipose (fat) tissue; the most common being the Body Mass Index (BMI) (see below). A fat cell is an endocrine cell and adipose tissue is an endocrine organ. As such, adipose tissue secretes a number of products, including metabolites, cytokines, lipids, and coagulation factors among others. Significantly, excess adiposity or obesity causes increased levels of circulating fatty acids and inflammation. This can lead to insulin resistance, which in turn can lead to type 2 diabetes.

The biology of food intake is very complex, involving olfaction (smell), taste, texture, temperature, cognitive and emotional responses and metabolic/autonomic information, which signal the brain to initiate or cease eating. Recent scientific studies have identified several substances that act on the brain to signal a need for an increase in food intake. Likewise, several substances have been identified that signal the brain to decrease food intake.

Obesity is a disease that affects more than one-third of the U.S. adult population (approximately 78.6 million Americans). The number of Americans with obesity has steadily increased since 1960, a trend that has slowed in recent years but shows no sign of reversing. Today, 69 percent of U.S. adults are categorized as being affected by obesity or having excess weight.

According to NIH, the combination of poor diet and physical inactivity are the second leading cause of preventable death in the U.S., causing an estimated 300,000 deaths per year. Obesity puts individuals at risk for more than 30 chronic health conditions. They include: type 2 diabetes, high cholesterol, hypertension, gallstones, heart failure, fatty liver disease, sleep apnea, GERD, stress incontinence, heart failure, degenerative joint disease, birth defects, miscarriages, asthma, and numerous cancers.

The healthcare costs of American adults with obesity amount to approximately $190 billion per year. Discrimination and mistreatment of person with obesity is widespread and, sadly, often considered socially acceptable.

Obesity is increasing around the world. High body mass index now ranks with major global health problems such as childhood and maternal under-nutrition, high blood pressure, high cholesterol, unsafe sex, iron deficiency, smoking, alcohol and unsafe water in total global burden of disease.

For people with obesity, weight loss based solely on lifestyle changes can be very difficult to achieve and even more challenging to maintain. Supporting strategies, such as obesity medications, can be important tools for effectively treating obesity in some individuals. Given the complex nature of the disease, no single drug is likely to fix the epidemic. Additional research and development efforts are needed for obesity treatments – as there are more than 100 drugs available for related diseases, like hypertension, but only 4 medications approved for the long-term treatment of obesity.


What Is BMI?
 
Body Mass Index (BMI) is a mathematical calculation involving height and weight, irrespective of family history, gender, age or race. BMI is calculated by dividing a person's body weight in kilograms by their height in meters squared (weight [kg] height [m]2) or by using the conversion with pounds (lbs) and inches (in) squared as shown below, This number can be  misleading, however, for very muscular people, or for pregnant or lactating women.

                  [Weight (lbs) ÷ height (in)2  ] x 704.5 =BMI
              
BMI calculator

The BMI cutoffs are:

Below 18.5                    Underweight
18.5-24.9                      Normal weight
24.5-29.9                      Overweight
30 and greater               Obese
40 and greater               Morbid or extreme obesity    

BMI is frequently used in population studies because of its ease of determination and well-supported association with mortality and health effects. However, other measures of excess adipose tissue, such as waist circumference, waist-to-hip ratio and others are also used. Individuals may need to use additional factors to assess their individual risk including family history, level of physical activity, smoking and dietary habits.

 

Waist Circumference

Waist circumference is another widely used measurement to determine abdominal fat content. An excess of abdominal fat, when out of proportion to total body fat, is considered a predictor of risk factors related to obesity. Men with a waist measurement exceeding 40 inches are considered at risk. Women are at risk with a waist measurement of 35 inches or greater.

 

References:

1. Ogden CL, Carroll MD, McDowell MA, Flegal KM. Obesity among adults in the United States— no change since 2003–2004. NCHS data brief no 1. Hyattsville, MD: National Center for Health Statistics. 2007 http://www.cdc.gov/obesity/data/index.html

2. Katherine M. Flegal; Barry I. Graubard; David F. Williamson; Mitchell H. Gail.  Excess Deaths Associated With Underweight, Overweight, and ObesityJAMA, April 20, 2005; 293: 1861 - 1867.

3. Eric A. Finkelstein, Justin G. Trogdon, Joel W. Cohen, William Dietz, [Health Affairs 28, no. 5 (2009): w822-w831 (published online 27 July 2009; 10.1377/hlthaff.28.5.w822)]

 

 

(Please note: External Links are provided as a courtesy. The Obesity Society is not responsible for the content on sites accessed through external links.)
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