Skip Navigation


Last Updated: Mar 1, 2019


An obese person has more body fat than what is considered normal for his or her height. Although sometimes used interchangeably, the term “overweight” refers to increased body weight from fat, muscle, bone and fluids, while “obese” only refers to excess fat.

Obesity, which is the disease of carrying excess fat, affects one third of Americans (about 78.6 million) and is a leading cause of mortality and soaring healthcare costs in the country. This is because obesity increases the risk of developing a myriad of chronic diseases including heart disease, high cholesterol, hypertension, liver disease, type 2 diabetes, respiratory disorders, sexual dysfunction, osteoarthritis and some cancers. Additionally, obese people are more likely to suffer from depression, social isolation and physical limitations.

Obesity is the result of an imbalance between calorie intake and calorie expenditure. Genetics, a high-calorie diet and low physical activity are all contributors to a buildup of body fat. Dietary and lifestyle trends that cause obesity are showing global impact, with both adulthood and childhood obesity on the rise around the world. Over the last 30 years in the United States, the numbers of obese children in the 6-11 and 12-19 age groups have more than doubled and quadrupled, respectively.

With lifestyle changes and medication, it is possible to achieve a healthy weight and avoid secondary diseases; even modest weight loss can delay or prevent associated complications. Surgical procedures that force a limit on the amount of food intake or slow fat absorption are also available.

Causes and Risk Factors

The body stores excess fat as a result of too much caloric intake and a lack of calorie expenditure through physical activity. Poor diet and inactivity are often influenced by environmental factors like community behavior and socioeconomics. Genetics and other health conditions may also play a role. Known causes and risk factors for obesity include:


The symptoms of obesity include:

Diagnosis and Treatment

Doctors diagnose obesity by performing a general exam and learning about the patient’s personal/family medical history. The body mass index (BMI) and waist circumference are routinely used to estimate “fatness”. The BMI is calculated by dividing a person’s weight (kilograms) by the square of their height (meters); it is solely an estimate and not a direct measurement for body fat. The BMI is associated with weight in the following way:

Excess abdominal fat is also reflected in the waist circumference. The risk of obesity and related complications increases when the waist circumference measures over 35 inches for women, and over 40 inches in men.

Obesity is treated by achieving and maintaining a healthy weight through a combination of diet, exercise, medication and, in some cases, surgery. At-risk or obese children are encouraged to eat healthy and increase physical activity. Obese adults are advised to lose 5-10 percent of their body weight as an initial step in a comprehensive treatment plan that includes:


The best way to maintain a healthy weight is through regular exercise and a balanced diet that is low in saturated fats and added sugars. It is also important to address medical or environmental factors that trigger hunger and inactivity.


Additional Resources

Home Health Testing Guides

Testing Company Reviews

Related Topics

Tina Shahian, PhD

Tina is a writer for Innerbody Research, where she has written a large body of informative guides about health conditions.


A communication specialist in life science and biotech subjects, Tina’s successful career is rooted in her ability to convey complex scientific topics to diverse audiences. Tina earned her PhD in Biochemistry from the University of California, San Francisco and her BS degree in Cell Biology from U.C. Davis. Tina Shahian’s Linkedin profile.


In her spare time, Tina enjoys drawing science-related cartoons.