What is obesity?

Obesity is a medical condition where the body stores an excessive amount of body fat. If you have a BMI over 30, you are considered obese.

People who are overweight or obese are at a much higher risk of developing cancer, type-2 diabetes, high blood pressure and heart disease.

More than 35 percent of adults are obese (78 million adults).

Common related conditions
Adolescent Obesity Childhood Obesity

Causes of obesity

Obesity is most commonly caused by overeating and inactivity. If you regularly eat more calories than you burn through activity, you will likely gain weight. Continuing this habit over months or years can lead to obesity.

Other causes that contribute to obesity include:

  • Diet — diets high in simple carbohydrates, such as sugars, fructose, soft drinks and beer, can increase blood glucose levels, stimulate insulin production and therefore cause weight gain.
  • Medications — a variety of medications can cause weight gain including antidepressants, anticonvulsants and corticosteroids.
  • Diseases — conditions such as hypothyroidism, insulin resistance and Cushing’s syndrome can contribute to obesity.

Risk factors for obesity

  • Genetics — children of two obese parents are more likely to become obese as well.
  • Inactive lifestyle in combination with poor eating habits — people who lead an inactive lifestyle and regularly eat high calorie meals are more likely to become obese.
  • Social factors — social factors, such as poverty, can put people at higher risk for becoming obese. People who have less income are more likely to eat high-calorie processed foods more often.
  • Quitting smoking — if you have recently quit smoking, you are more likely to gain weight. Nicotine increases metabolism to burn more calories.

Symptoms of obesity

The most common sign of obesity is the presence of excess fat on the body. Other health problems that obesity can cause include:

  • Snoring
  • Increased breathlessness
  • Fatigue
  • Orthopedic back and joint pain
  • Inability to perform daily activities

Diagnosis of obesity

Obesity can be diagnosed in a physical exam with your primary care doctor. In the exam, your physician will take your medical history, calculate your BMI (body mass index), measure the size of your waist and potentially order tests to rule out other medical conditions. Obesity is typically defined as a person who has a BMI over 30.

BMI weight categories include:

Weight category Adults
Underweight Below 18.5
Healthy weight 18.5 to 24.9
Overweight 25 to 29.9
Obese Over 30

Treatment for obesity

Treatment for obesity depends on the cause of the obesity and severity of your condition. Your doctor will likely recommend lifestyle changes as a first-line therapy, and if unsuccessful, he or she may also recommend medications, behavioral weight loss treatments and/or surgery.

Healthy lifestyle changes

Your doctor may recommend specific lifestyle modifications to help you lose weight and develop healthy habits. Recommendations may include:

Healthy eating

Your doctor may recommend a healthy eating regime that is full of fresh fruits, vegetables, grains and healthy fats. To lose weight, you should consume fewer calories than your body burns daily.


Exercise is an integral part of a healthy weight loss plan. Your doctor will likely recommend increasing your physical activity level to lose weight.

Healthy sleep

Research shows a strong correlation between sleep deprivation and obesity. Your doctor may recommend maintaining a healthy sleep schedule in order to lose weight.

Behavioral weight-loss programs

Some patients may benefit from a structured weight loss program led by a trained healthcare professional. Behavioral weight-loss programs combine healthy diet plans, an exercise program and behavioral treatments.


If lifestyle modifications are not effective, your doctor may prescribe weight loss medications. Medications are not recommended as a stand-alone treatment for weight loss but should be used in conjunction with lifestyle changes.

Surgical procedures

In extreme cases, surgical weight loss surgery may be necessary. Surgical weight loss procedures are used as a last resort after all other treatment options have been exhausted.

Types of surgical weight loss surgeries include:

Gastric bypass surgery

During gastric bypass surgery, a part of the stomach is connected to the middle of the intestine. This procedure decreases the amount of food you can eat to help you lose weight.


Gastrectomy surgery leads to weight loss by decreasing the amount of food you can eat.  During the procedure, your surgeon will remove a portion of the stomach.

Gastric banding

During a gastric banding procedure, a band is placed around the upper portion of the stomach to make the stomach smaller. Patients are unable to eat as much and typically lose weight.

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