Weight loss surgery: clearing up the confusion

Here are terms you might encounter if you are just starting to research weight loss surgery, or if you are planning to bring up the topic with your doctor.

Body Mass Index (BMI): An established measure that divides your weight (in kilograms) by your height (in meters squared). You can find BMI calculators for adults or teenagers online. To be a candidate for bariatric surgery, you must have a BMI of 40 or higher, or a BMI of 35 to 39 along with one or more medical conditions, such as diabetes, hypertension, or sleep apnea. Teenagers can have bariatric surgery if they have reached their adult height, are past puberty, and meet one of the qualifications listed above. This an important measure as life expectancy declines as BMI increases, says Dr. Morton.

Obesity
: A medical condition in which a person has too much body fat for their height, increasing their chance of developing additional medical problems. Obesity is not just caused by eating too much; genetics is a contributing factor, as well as environmental, physiologic, and metabolic issues, and certain medications. A person has Class 1 obesity if they have a BMI of 30 to < 35, Class 2 if it is 35 to < 40, and Class 3 if it is 40 or more.

Overweight: When a person weighs more than is optimal for their height. Adults with a BMI of 25 to 30 are considered overweight. Overweight people have too much weight, some of which may come from fat, as well as water, bone, or muscle. “If you’re overweight, you still have recourse,” Dr. Morton says. “It’s still possible to take care of that with dieting.” Some people in this group, such as athletes, may have a lot of muscle weight, and therefore not as much fat, and will not necessarily have an increased risk of health problems due to their weight.

Waist size
: Another measure of overweight and obesity that weight loss surgeons take into account. Generally, waist sizes greater than 35 inches in women and more than 40 inches in men put them at higher risk for type 2 diabetes and heart disease. People with “apple-shaped” bodies (a waist that is bigger than their hips) also have an increased risk for these conditions, which can occur at lower waist sizes for patients of Asian descent, says Dr. Morton. 

Metabolism
: An umbrella term referring to all the chemical and physical processes in the body that convert or use energy. This includes the process of burning calories. Bariatric surgery can boost metabolism, which can lead to dramatic weight loss.

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Hormones: Chemical messengers in the body that travel in the bloodstream to tissues and organs to control different activities such as growth, mood, and metabolism. Bariatric procedures often cause hormonal changes that, in turn, reduce hunger, increase satiety, and boost metabolism.

Co-morbidity: A medical condition that is simultaneously present with one or more other conditions. Obesity is considered a morbidity, and co-morbidities may help determine the course of a person’s treatment for their obesity. “The biggest ones we tend to encounter fall into the category of metabolic syndrome,” says bariatric surgeon Andrew Duffy, MD. “Metabolic syndrome is a constellation of insulin resistance, visceral adiposity, hypertension, and lipid abnormalities.”

Bariatric surgery: Another umbrella term, this time describing the category of procedures that work mainly by changing the anatomy and size of the stomach to limit the amount of food you take in, and, in some cases, altering the digestion process to improve fat metabolism. Some procedures impact the production of intestinal hormones that affect appetite.

Laparoscopic surgery: A minimally invasive surgery that involves making small incisions in the abdomen and inserting narrow tubes with long instruments attached. For patients, this approach means less pain and scarring, and a speedier recovery. While laparoscopic surgery is not optimal for every patient, over 99% of bariatric surgeries at Yale can be performed using this approach, says Dr. Morton.  


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