Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classified as obese when their body mass index (BMI)—a person's weight divided by the square of the person's height—is over 30 kg/m2; the range 25–30 kg/m2 is defined as overweight. Some East Asian countries use lower values to calculate obesity. Obesity is a major cause of disability and is correlated with various diseases and conditions, particularly cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.
Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat, or lean mass. Weight loss can either occur unintentionally because of malnourishment or an underlying disease, or from a conscious effort to improve an actual or perceived overweight or obese state. "Unexplained" weight loss that is not caused by reduction in calorific intake or increase in exercise is called cachexia and may be a symptom of a serious medical condition.
Gastric bypass surgery refers to a technique in which the stomach is divided into a small upper pouch and a much larger lower "remnant" pouch, where the small intestine is rearranged to connect to both. Surgeons have developed several different ways to reconnect the intestine, thus leading to several different gastric bypass procedures (GBP). Any GBP leads to a marked reduction in the functional volume of the stomach, accompanied by an altered physiological and physical response to food.
Bariatrics is a discipline that deals with the causes, prevention, and treatment of obesity, encompassing both obesity medicine and bariatric surgery.
David S. Ludwig is an American endocrinologist and low-carbohydrate diet advocate in Boston, Massachusetts. He is a promoter of functional medicine.
A very-low-calorie diet (VLCD), also known as semistarvation diet and crash diet, is a type of diet with very or extremely low daily food energy consumption. VLCDs are defined as a diet of 800 kilocalories (3,300 kJ) per day or less. Modern medically supervised VLCDs use total meal replacements, with regulated formulations in Europe and Canada which contain the recommended daily requirements for vitamins, minerals, trace elements, fatty acids, protein and electrolyte balance. Carbohydrates may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. Medically supervised VLCDs have specific therapeutic applications for rapid weight loss, such as in morbid obesity or before a bariatric surgery, using formulated, nutritionally complete liquid meals containing 800 kilocalories or less per day for a maximum of 12 weeks.
Bariatric surgery is a surgical procedure used to manage obesity and obesity-related conditions. Long term weight loss with bariatric surgery may be achieved through alteration of gut hormones, physical reduction of stomach size, reduction of nutrient absorption, or a combination of these. Standard of care procedures include Roux en-Y bypass, sleeve gastrectomy, and biliopancreatic diversion with duodenal switch, from which weight loss is largely achieved by altering gut hormone levels responsible for hunger and satiety, leading to a new hormonal weight set point.
The American Society for Metabolic & Bariatric Surgery (ASMBS) is a non-profit medical organization dedicated to metabolic and bariatric surgery, and obesity-related diseases and conditions. It was established in 1983.
George L. Blackburn was the S. Daniel Abraham Professor of Nutrition and associate director of the division of nutrition at Harvard Medical School. He was also director of the Center for the Study of Nutrition Medicine (CSNM) in the Roberta and Stephen R. Weiner Department of Surgery, and director of the new Feihe Nutrition Laboratory at Beth Israel Deaconess Medical Center (BIDMC), Boston, Massachusetts.
Management of obesity can include lifestyle changes, medications, or surgery. Although many studies have sought effective interventions, there is currently no evidence-based, well-defined, and efficient intervention to prevent obesity.
Henry Buchwald is an Austrian-American surgeon and academic. He is the Professor of Surgery and Biomedical Engineering and the Owen and Sarah Davidson Wangensteen Chair in Experimental Surgery Emeritus at the University of Minnesota, Minneapolis, Minnesota.
Obesity medicine is a field of medicine dedicated to the comprehensive treatment of patients with obesity. Obesity medicine takes into account the multi-factorial etiology of obesity in which behavior, development, environment, epigenetic, genetic, nutrition, physiology, and psychosocial contributors all play a role. As time progresses, we become more knowledgeable about the complexity of obesity, and we have ascertained that there is a certain skill set and knowledge base that is required to treat this patient population. Clinicians in the field should understand how a myriad of factors contribute to obesity including: gut microbiota diversity, regulation of food intake and energy balance through enteroendocrine and neuroregulation, and adipokine physiology. Obesity medicine physicians should be skilled in identifying factors which have contributed to obesity and know how to employ methods to treat obesity. No two people with obesity are alike, and it is important to approach each patient as an individual to determine which factors contributed to their obesity in order to effectively treat each patient. Physicians specializing in obesity medicine may choose to obtain board certification by the American Board of Obesity Medicine.
Thomas A. Wadden is a clinical psychologist and educator who is known for his research on the treatment of obesity by methods that include lifestyle modification, pharmacotherapy, and bariatric surgery. He is the Albert J. Stunkard Professor of Psychology in Psychiatry at the Perelman School of Medicine at the University of Pennsylvania and former director of the university's Center for Weight and Eating Disorders. He also is visiting professor of psychology at Haverford College.
Arghavan Salles is an Iranian American bariatric surgeon. Salles is a Director of the American Medical Women's Association, a Special Advisor for DEI Programs in the Department of Medicine at Stanford University School of Medicine and a Senior Research Scholar at the Clayman Institute for Gender Research. Salles' research focuses on gender equity, well-being, and the challenges women face in the workplace. Salles works as an advocate for equity and inclusion and as an activist against sexual harassment. Salles is an international speaker who worked on the front lines and supported health professionals during the COVID-19 pandemic through social media.
The American Board of Obesity Medicine (ABOM) is a 501(c)(3) nonprofit, self-appointed physician-evaluation organization that certifies physicians practicing obesity medicine. The American Board of Obesity Medicine is not a membership society, educational institution, or licensing body. Certification is intended to signify that a physician possess specialized knowledge of obesity. Eligibility requires completion of a recognized fellowship program or sufficient continuing medical education (CME).
The National Board of Physician Nutrition Specialists (NBPNS) is a nonprofit organization that certifies physicians practicing nutrition medicine. Established in 1997, NBPNS maintains credentialing standards, examination assessments, and offers certification for physician nutrition specialists. Eligibility requires completion of a recognized nutrition fellowship program, sufficient continuing medical education (CME), or comparable training. The NBPNS is affiliated with the American Society for Nutrition. Member societies include: the American Society for Parenteral and Enteral Nutrition, the American Association of Clinical Endocrinologists, American Society for Clinical Nutrition, North American Association for the Study of Obesity, American College of Nutrition, American Gastroenterological Association, and the Canadian Society for Clinical Nutrition.
Marcella Alsan is an American physician and economist at Harvard Kennedy School. She is known for her works in the field of health inequality and development economics. She is currently a professor of Public Policy at the Harvard Kennedy School and was previously an associate professor of medicine at Stanford University. She uses randomized evaluations and historical public health natural experiments to study how infectious disease, human capital, and economic outcomes interact. She has studied the effects of the Tuskegee Syphills Experiment on health care utilization and mortality among Black men. Alsan was awarded a MacArthur Fellowship in 2021.
Rachel Louise Batterham is a British physician who is a professor of Obesity, Diabetes and Endocrinology at University College London. She established the University College London Hospitals NHS Foundation Trust Bariatric Centre for Weight Management and Metabolic Surgery. She has extensively studied obesity, and has contributed to clinical management and the understanding of obesity-related diseases.
Emily Louise Breza is an American development economist currently serving as the Frederic E. Abbe Professor of Economics at Harvard University. She is a board member at the Abdul Latif Jameel Poverty Action Lab, and an affiliated researcher at the International Growth Centre and National Bureau of Economic Research. Breza's primary research interests are in development economics, in particular the interplay between social networks and household finance. She is the recipient of a Sloan Research Fellowship.
Rinki Murphy is a New Zealand endocrinologist, and is a full professor of molecular medicine at the University of Auckland, specialising in diabetes pathophysiology and precision medicine.
