An Overview of Obesity By Yasmine Ali, MD - Reviewed by a board-certified physician. Updated July 28, 2016 The term 'obesity' gets thrown around a lot, and sometimes it may not be clear what it means. Does it refer to anyone who is overweight or has some excess weight to lose? Or is it more than that? There is a medical definition for obesity, as well as overweight, and knowing the distinctions is important for your health.What Is Obesity?The medical definition for obesity hinges on the calculation of body mass index (BMI). A normal BMI is defined as falling between 18.5 and 24.9 kilograms per meters squared. The condition known medically as overweight is defined as a BMI of 25.0 to 29.9, and once BMI hits 30.0, that triggers the official medical definition of obesity. The diagnosis of morbid obesity is applied at a BMI of 40.0 or greater.Importantly, obesity has now been recognized as a disease in and of itself. In 2013, the American Medical Association (AMA) officially declared it as such, acknowledging the “enormous humanitarian and economic impact of obesity as requiring the medical care, research and education attention of other major global medical diseases.” Article The Pros and Cons of Weight Loss Surgery Article 3 Ways to Get Immediate Weight Loss Results In fact, the obesity epidemic is one of the biggest public health problems of our time. According to the World Health Organization (WHO), more than one billion adults worldwide are overweight, and at least 300 million of those adults meet the medical definition of obesity. Further, the WHO estimates that obesity accounts for two percent to six percent of all healthcare costs in several developed nations, and its prevalence in many European countries has tripled since the 1980s. Even developing nations are now affected and, in many instances, are seeing a rate of increase in overweight and obesity that is faster than in developed nations. Five Things to Know About Obesity1) There Are Many Causes of ObesitySome are genetic, and many are environmental. Environmental causes include lifestyle factors such as leading a sedentary lifestyle, consuming added sugars, dining out too frequently, and not getting enough sleep, among others. Some medications and medical conditions can also lead to weight gain.2) Obesity Is PreventableAs with many chronic diseases, such as diabetes and cardiovascular disease (both of which are also linked to obesity), obesity is largely—if not almost entirely—preventable. Strategies for preventing obesity include being aware of your risk factors, being vigilant about adhering to a healthy diet, making time for daily exercise, and staying in motion throughout the day.3) Obesity Is a Risk Factor for Several Other Chronic DiseasesObesity and overweight have been linked to several kinds of cancer, heart disease, stroke, high blood pressure, diabetes, obstructive sleep apnea, and even infertility. Unfortunately, and perhaps for the first time in history, overweight and obesity are now responsible for more deaths worldwide than malnutrition or being underweight. Article Why You Should Try the Mediterranean Diet Article How the Latest Weight Loss Drugs Can Affect Your Heart Globally, according to WHO statistics, 44 percent of diabetes, 23 percent of ischemic heart disease, and as much as 41 percent of certain cancers can be attributed to overweight and obesity.The good news is that weight loss and treatment of obesity can reverse these risks. Research has found that losing just 5 percent to 10 percent of excess weight can result in a dramatic reduction in the risk for obesity-related illnesses. And getting daily exercise, regardless of associated weight loss, has far-reaching health benefits.4) Childhood Obesity Is a Global Health ProblemChildhood obesity has been on the rise in the United States for several years now, and, according to the American Heart Association (AHA), approximately one in three children and teenagers is obese or overweight.As the AHA notes, this rate is nearly triple what it was in 1963. In fact, childhood obesity has become so alarmingly prevalent and such a threat to children’s health that the American Academy of Pediatrics now has an entire website dedicated to prevention and treatment. This is undoubtedly hard for any parent to hear. If you are concerned that your child may have overweight or obesity, be sure to discuss your worry with your child's pediatrician and ask for help with strategies that can lead to weight loss that are appropriate for your child and your situation.If your child has been given a diagnosis of obesity, you can work with your child in a positive way to make daily physical activity more fun (especially if he or she does not have access to physical education at school), and to encourage healthy eating habits. This includes taking steps to encourage healthier habits on holidays that are traditionally associated with sugar consumption, like Halloween and Easter, and making it a priority to eat at home more often.Also take care to eliminate sugared beverages from your child's diet, and look for family-friendly activities that involve exercise, particularly outdoors.5) A Variety of Treatments Are Now Available for ObesityThese range from diet and lifestyle changes to anti-obesity medications, medical devices, and surgical procedures that induce weight loss, like bariatric surgery. Article Is Weight-Loss Surgery Underutilized? Article Low-Fat vs. Low-Carb: Which Is Better for Weight Loss? According to the 2013 obesity guidelines released by the AHA, the American College of Cardiology (ACC), and The Obesity Society (TOS), bariatric surgery is an option for those with obesity who have already tried diet and lifestyle changes and anti-obesity medications, and still have a BMI of 40 or greater, or a BMI of 35 or greater with at least one other medical condition known to be caused by obesity.In the United States, the most popular form of bariatric surgery (also known as “weight-loss surgery”) is the gastric sleeve procedure (also known as sleeve gastrectomy).If You’ve Been Recently Diagnosed With ObesityYou may have calculated your own BMI using any of a number of online BMI calculators out there and determined that you have obesity, or perhaps you have been told so by your physician or other healthcare professional.It is best to discuss what your next steps for treating your obesity should be with your physician. Usually, changes to your diet and physical activity level will be recommended first.There are also support groups and networks that can help. Overeaters Anonymous, for instance, is a community-based support group modeled on a 12-step program. Meetings are held worldwide, and members can remain anonymous.Additionally, if you think you may be an addictive eater, there is Food Addicts Anonymous, another support group that can help, especially if you find yourself engaging in eating-disordered behaviors or turning to food for emotional reasons.The important thing to remember is that obesity is treatable. While it will take dedication and commitment on your part, as well as serious and well-thought-out changes to your usual lifestyle, you should never give up—the benefits to your long-term health are far too significant.Remember that research has found that losing just 5 percent to 10 percent of your body weight if you are overweight or obese can make a tremendous difference in your health. These include improvements in risk factors for cardiovascular disease, such as high cholesterol and high blood pressure, as well as a greatly reduced risk of developing type 2 diabetes.Next Steps to ConsiderIf you’ve been diagnosed with obesity, be sure to undergo any bloodwork your physician recommends, especially blood sugar, liver, and thyroid tests, which can uncover diseases related to obesity.According to the U.S. Preventive Services Task Force (USPSTF), screening for diabetes by checking blood sugar is recommended for adults who have overweight or obesity and are between the ages of 40 to 70 years. Ideally, this would be done annually as part of the routine health exam and cardiovascular risk assessment.A Word From VerywellLiving with obesity can be difficult. But remember—fortunately, obesity is treatable and can be reversed. Any small changes you can make will be worth it. This can be done through diet and lifestyle changes, medications, surgical procedures, or a combination of the above. You are not alone. Remember that, given the high prevalence of obesity and overweight in the world today, the majority of people in the United States and around the world are sharing this journey and this struggle with you. Never give up.Sources:2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society [published online November 27, 2013]. Circulation.American Medical Association House of Delegates: Resolution 420 – Recognition of Obesity As a Disease. Accessed March 7, 2014. Jensen MD, Ryan DH, Apovian CM, et al.Fontaine KR, Redden DT, Wang C, et al. Years of Life Lost Due to Obesity. JAMA 2003;289:187-193.Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of Childhood and Adult Obesity in the United States, 2011-2012. JAMA. 2014;311(8):806-814.Olshansky SJ, Passaro DJ, Hershow RC, et al. A Potential Decline in Life Expectancy in the United States in the 21st Century. N Engl J Med 2005;352:1128-1145.Siu AL; U.S. Preventive Services Task Force. Screening for Abnormal Blood Glucose and Type 2 Diabetes Mellitus: U.S. Preventive Services Task Force Recommendation Statement. Ann Intern Med 2015;163:861-8.Tuomilehto J, Lindstrom J, Eriksson JG, et al. Prevention of Type 2 Diabetes Mellitus by Changes in Lifestyle Among Subjects with Impaired Glucose Tolerance. N Eng J Med 2001;344:1343-1350.World Health Organization. 10 Facts on Obesity. Accessed online at http://www.who.int/features/factfiles/obesity/facts/en/index3.html on October 2, 2014.