what is obesity / obesity as a disease

Definition of Obesity

Obesity used to be considered a cosmetic problem, the result of overeating and too little self-control. The World Health Organization and medical societies worldwide now understand it differently: obesity is a multifactorial disease with a strong genetic component that is both progressive and chronic. Genetics play a role through metabolic, behavioral, cultural, hormonal, and psychological factors that cause fat accumulation and lead to weight gain.

A Chronic Disease

Alongside the genetic component, hormonal, metabolic, psychological, cultural, and behavioral factors promote fat accumulation and weight gain, which leads to more weight gain — and ultimately to obesity. This is why obesity is considered a progressive, chronic disease requiring lifelong treatment and control.

More than 100 million American adults have obesity today, and over 40% of U.S. adults are affected. Obesity and overweight together are among the leading preventable causes of death in the United States, according to the CDC.

Obesity is a costly disease that affects people financially, physically, and emotionally. It's also progressive — it tends to get worse over time — and it's the root cause of many health problems, including high blood pressure, diabetes, and heart disease.

Positive Energy Balance

A positive energy balance leads to weight gain, occurring when the calories taken in exceed the calories the body uses for basic biological function, daily activity, and exercise. Overeating and lack of exercise both contribute to a positive energy balance, but they aren't the only causes.

Other factors affect energy balance and fat accumulation independent of overeating or being sedentary, including:

Not getting enough sleep. Eating foods that, beyond their calorie count, cause hormonal or metabolic changes that increase body fat — foods high in processed grains, sugar, fat, high fructose corn syrup, and processed meats. Not eating enough of the foods that help fight fat, including legumes, vegetables, fruits, seeds, nuts, and high-quality protein. Heavy stress or psychological strain. Certain medications. Exposure to certain pollutants.

Prevalence of Obesity

The World Health Organization estimates that about 65% of the world's population lives in countries where more people die from obesity-related causes than from being underweight. Worldwide, about 500 million adults are affected by obesity, with nearly a billion adults and 48 million children affected by being overweight.

In the United States, more than 40% of adults age 20 and older have obesity, according to the CDC's most recent national data. Severe obesity affects about 9% of adults. Obesity rates have risen substantially over the past several decades — in 1990, most states had an obesity prevalence of 10% or less. Today, the CDC's state-level data shows at least 1 in 4 adults in every U.S. state and territory has obesity, with many states above 35%.

Measuring Obesity and Body Mass Index (BMI)

Obesity is marked by the accumulation of excess body fat. There are devices that measure fat versus lean tissue directly, but they're expensive and time-consuming. The practical alternative is to estimate body fat based on height, build, and weight. Ideal Body Weight (IBW) and Body Mass Index (BMI) are the two measures most often used.

IBW comes from the Metropolitan Life Insurance Company Table and accounts for body frame in addition to weight, though body frame is considered a somewhat arbitrary measure by many experts.

BMI is the more commonly used measure today. It estimates excess body fat based on height and weight, though it has real limitations — it doesn't distinguish between fat and muscle, doesn't account for where fat is distributed in the body, and is less reliable for athletes, bodybuilders, older adults, and pregnant women.

BMI categories, based on the association between BMI and health risk:

Normal weight: 18.9 to 24.9. Overweight: 25 to 29.9. Class I Obesity: 30 to 34.9. Class II, Serious Obesity: 35 to 39.9. Class III, Severe Obesity: 40 and above.

Lower BMI

A BMI between 30 and 40 sits at the lower end of the obesity spectrum, but it still carries real risk of obesity-related health problems. Patients in this range historically had fewer treatment options — primarily diet and exercise — since bariatric surgery typically requires a BMI of at least 35 with a related health condition, or 40 without one.

Causes of Obesity

Obesity results from a positive energy balance: when calorie intake exceeds what the body uses. Overeating and lack of exercise are part of this, but genetic, hormonal, metabolic, environmental, behavioral, and cultural factors all play a role too. Medications, inadequate sleep, certain medical conditions, pregnancy, and metabolism itself can all contribute.

Consequences and Quality of Life

More than 30 health conditions are linked to obesity, including high cholesterol, sleep apnea, type 2 diabetes, hypertension, gastroesophageal reflux disease (GERD), heart disease, numerous cancers, asthma, and other respiratory problems.

Obesity also affects quality of life broadly — it's connected to shame, depression, sexual problems, guilt, social isolation, and reduced performance at work.

Economic Impact

Obesity is expensive on both a personal and a national level. According to the CDC, obesity accounts for nearly $173 billion in medical expenditures annually. Adults with obesity have medical costs about $1,861 higher per year than adults at a healthy weight — and for those with severe obesity, the difference is about $3,097 per year.

Obesity is a progressive, chronic disease. It's also preventable, and for most patients, reversible.

If you're concerned about your weight, contact our office to learn more about obesity and how you can take charge of improving your weight and your health.