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What is Obesity?

In recent years, we have slowly begun to understand obesity as a disease — a chronic disease that requires medical attention. We now believe that obesity is a complex condition with genetic, environmental, cultural, and psychological causes. It is a mistake to "blame" extreme obesity on a simple lack of willpower.

In the United States alone, obesity affects one in five individuals in the general population. For many people with this devastating illness, diets alone rarely, if ever, produce lasting results.

Obesity is now the second leading cause of preventable death in the United States. The only preventable condition that kills more people than obesity is cigarette smoking.  It is estimated that about 300,000 people a year die from obesity and obesity-related disease.

Obesity-Related Illness

Extremely obese people have a shorter lifespan than non-obese people. Medical conditions associated with obesity include diabetes, high blood pressure, heart disease, sleep apnea, stroke, arthritis, and several types of cancer. Psychological effects can be equally devastating and include shame, guilt, and depression.

Losing weight can help improve and even eliminate some of these conditions or risks. For people with the most extreme forms of obesity, weight loss surgery may offer hope for significant, lasting weight loss. The surgery provides the extra help that many people with extreme obesity need. It creates changes in the digestive system that help patients alter their eating habits, becoming part of a comprehensive, life-long health plan that includes other components such as regular exercise, healthy food choices, and close, ongoing monitoring by members of a health care team.  

A Drastic Way to Lose Weight?

The decision to have a weight loss surgery (WLS) procedure should be made carefully. It should be made only with a full understanding of the risks and benefits of the procedure, the knowledge and willingness to accept the lifestyle changes imposed by the procedure and committing to life-long follow-up with the bariatric team. 

It is strongly recommended that you speak with others who have had a similar operation, research the issues on your own, and attend an information session prior to your initial appointment.

Following weight loss surgery, patients experience improvement in obesity-related illnesses, such as type 2 diabetes and hypertension, and the risk of early death is diminished. For seriously obese patients who have been unsuccessful in non-surgical weight loss methods such as diets, medications, behavior modification, or exercise programs, weight loss surgery may be a life-saving intervention — for many patients, the risks of remaining obese are more significant than the risks of complications from surgery.

Body Mass Index (BMI)

Surgical treatment for obesity is not for everyone who is overweight.  It is usually reserved for people who have so-called "severe obesity." We use a tool called body mass index (BMI) to measure the level of obesity.

What does BMI mean?

The BMI takes both height and weight into account, so it gives a more accurate picture of body size than weight alone. In general, we use the following categories of BMI when we talk about body weight:

  • Underweight = BMI less than 18.5
  • Normal weight = BMI between 18.5 and 24.9
  • Overweight = BMI between 25 and 29.9
  • Obesity = BMI of 30 or greater
    • Class I Obesity = BMI 30-35
    • Class II Obesity = BMI 35-40
    • Class III Obesity = BMI above 40

What's My BMI?
Use the BMI calculator »

At BIDMC, we use BMI to help us decide if someone might benefit from weight loss surgery. The surgery is not usually performed on someone with a BMI of less than 40, though there are important exceptions. For example, if there are serious medical problems related to weight, the surgery may be considered in someone with a BMI between 35 and 40. (Weight loss surgery is not done on anyone whose BMI is less than 35.)

Contact Information

Weight Loss Surgery Center
Beth Israel Deaconess Medical Center
Shapiro Clinical Center, 3rd Floor
330 Brookline Avenue
Boston, MA 02215