What Is Obesity?

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Obesity is a disease characterized by abnormal or excessive fat accumulation that can impair health. It is a global health epidemic with more than 650 million people affected worldwide, according to the World Health Organization. Obesity is a contributing factor to many diseases, including diabetes, cardiovascular disease, musculoskeletal disorders, and certain cancers.

The medical definition of obesity is based on the calculation of body mass index (BMI), a formula of weight in kilograms divided by height in meters squared. People with a BMI of 30 or above are considered obese. Your doctor will also consider your BMI in the context of an overall health assessment.

obesity symptoms
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Obesity Symptoms

The primary symptom of obesity is an excessive or abnormal amount of body fat. Carrying around extra weight can also lead to other symptoms and concerns, including:

  • Feeling out of breath
  • Increased sweating
  • Snoring
  • Fatigue
  • Back and joint pain
  • Low confidence and self-esteem
  • Feelings of isolation
  • Depression
  • Sexual dysfunction

In addition, obesity can lead to other health problems including hypertension, high cholesterol, type 2 diabetes, and stroke. 


Obesity is caused by an energy imbalance between calories consumed and calories expended, although some people are more predisposed to obesity than others. 

Environmental factors that contribute to obesity include leading a sedentary lifestyle, consuming added sugars, dining out too frequently, and not getting enough sleep, among others. 

Obesity is sometimes due to a medical condition, such as thyroid disease, hormonal conditions, Prader-Willi syndrome, and Cushing syndrome. Psychological factors, including stress eating and eating disorders, can also play a role, but these are not common causes.

Many medications including antidepressants, hormonal birth control, steroids, pain medications (such as opiiods), and antihistamines can also contribute to weight gain by either slowing metabolism or increasing appetite.

For some people, obesity is strongly linked to genetics and family history. Researchers have identified specific gene mutations and biological changes associated with obesity.


A diagnosis of obesity is diagnosed based on your BMI. You can calculate your BMI on your own, but your doctor will also determine your height and weight and confirm your BMI in their office.

Results are evaluated as follows:

BMI Indication
18.5 to 24.9 Normal
25 to 29.9 Overweight
30 or greater Obese
40 or greater Morbidly obese

If your BMI is 25 or over (the threshold for overweight), talk to your doctor about the next steps for managing your weight.

BMI, however, is only a screening tool. It is based on height and weight, but does not consider factors like fitness level, muscle mass, or frame size. As such, it is possible, for example, for you to have a BMI that defines you as obese when you have significant muscle mass and are healthy.

Given this, BMI will be considered in the context of an overall health assessment when considering both obesity and related health risks.

Waist-to-Hip Ratio

During a physical exam, your doctor will also take body measurements including your waist and hip circumference.

The waist-to-hip ratio is used to assess body fat distribution and central obesity. Excessive abdominal fat is more metabolically active than fat in other areas of the body and is linked to health conditions including insulin resistance, which leads to type 2 diabetes, and heart disease. 

Your doctor will also ask questions about your personal and family health histories, review your medications, and order lab tests to root out possible causes, such as thyroid disease or hormonal imbalances.

Risk Assessments

According to the U.S. Preventive Services Task Force (USPSTF), screening for diabetes by checking blood sugar is recommended for adults who are overweight or obese and are between the ages of 40 to 70 years. Ideally, this would be done annually as part of the routine health exam and cardiovascular risk assessment.

If you are diagnosed with obesity, be sure to undergo any bloodwork your physician recommends, especially blood sugar, liver, and thyroid tests, which can uncover diseases related to obesity.


Weight loss is the primary objective of obesity treatment. Research shows losing just 5% to 10% of your body weight if you are overweight or obese can make a tremendous difference in your health and reduce your risk of cardiovascular disease and type 2 diabetes.

The first line of treatment for obesity is diet and exercise. Taking small steps toward a healthier lifestyle, such as cooking from scratch, eating more vegetables, and walking 10,000 steps a day, can make a big impact on weight loss. Many people with obesity find success on a medically supervised low-calorie weight loss plan.

A variety of treatments are now available for obesity and range from diet and lifestyle changes to anti-obesity medications, medical devices, and surgical procedures that induce weight loss, like bariatric surgery.

Medications to treat obesity include stimulants that reduce appetite and increase energy, antidepressants, and other drugs that work on brain chemistry to reduce food cravings, dietary fat blockers that reduce the absorption of fat, and combination medicines. Your doctor may consider these depending on the success of lifestyle changes, your weight and overall health profile, and other factors.

Bariatric surgery is an option for those with obesity who have already tried diet and lifestyle changes and anti-obesity medications and still have a BMI of 40 or greater, or a BMI of 35 or greater with at least one other medical condition known to be caused by obesity, according to the 2013 obesity guidelines released by the American Heart Association (AHA), the American College of Cardiology (ACC), and The Obesity Society (TOS).

In the United States, the most popular form of bariatric surgery (a.k.a. weight loss surgery) is the gastric sleeve procedure (also known as sleeve gastrectomy).


Living with obesity can be difficult. But remember—fortunately, obesity is treatable and can be reversed. Any small changes you can make will be worth it. This can be done through diet and lifestyle changes, medications, surgical procedures, or a combination of treatments.

The important thing to remember is you do not have to do it on your own. In addition to your medical team, there are support groups and networks that can help. For example, if you struggle with food, Overeaters Anonymous is a community-based support group modeled on a 12-step program. Meetings are held worldwide and members can remain anonymous.

Additionally, if you think you may be an addictive eater, there is Food Addicts Anonymous, another support group that can help, especially if you find yourself engaging in eating-disordered behaviors or turning to food for emotional reasons.

There are also myriad examples of friends and neighbors who join together to achieve shared health goals, such as walking groups. Gauge interest via social media or simply ask around. Even if someone you know doesn't need to lose weight, they may be more than eager to join you.

While it will take dedication and commitment on your part, as well as serious and well-thought-out changes to your usual lifestyle, you should never give up—the benefits to your long-term health are far too significant.


As with many chronic diseases, such as diabetes and cardiovascular disease, obesity is mostly preventable with a healthy lifestyle. Following a balanced, portion-controlled diet, making an effort to move more, finding healthy outlets for stress, and getting enough sleep can make a big difference in weight control.

While this is especially important for those with a family history of obesity, medical conditions that contribute to weight gain, and other risk factors, being committed to these strategies is important for everyone.

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Article Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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