The term bariatrics was coined around 1965, from the Greek root bar- ("weight" as in barometer), suffix -iatr ("treatment," as in pediatrics), and suffix -ic ("pertaining to"). The field encompasses dieting, exercise and behavioral therapy approaches to weight loss, as well as pharmacotherapy and surgery. The term is also used in the medical field as somewhat of a euphemism to refer to people of larger sizes without regard to their participation in any treatment specific to weight loss, such as medical supply catalogs featuring larger hospital gowns and hospital beds referred to as "bariatric."
The basic principle of bariatric surgery is to restrict food intake and decrease the absorption of food in the stomach and intestines.
The digestion process begins in the mouth where food is chewed and mixed with saliva and other enzyme-containing secretions. The food then reaches the stomach where it is mixed with digestive juices and broken down so that nutrients and calories can be absorbed. Digestion then becomes faster as food moves into the duodenum (first part of the small intestine) where it is mixed with bile and pancreatic juice.
Bariatric surgery is designed to alter or interrupt this digestion process so that food is not broken down and absorbed in the usual way. A reduction in the amount of nutrients and calories absorbed enables patients to lose weight and decrease their risk for obesity-related health risks or disorders.
Body mass index (BMI), a measure of height in relation to weight, is used to define levels of obesity and help determine whether bariatric intervention is required. Clinically severe obesity describes a BMI of over 40 kg/m2 or a BMI of over 35 kg/m2 in combination with severe health problems.
Health problems associated with obesity include type 2 diabetes, arthritis, heart disease, and severe obstructive sleep apnea. The Food and Drug Administration (FDA) approves the use of adjustable gastric banding for patients with a BMI of 30 kg/m2 or more who also have at least one of these conditions.