The proportion of the population who is overweight or obese has been increasing steadily for the past 40 years in the US (Flegal et al. 2016) and excess weight has reached epidemic proportions. Over 70% of the population is at least overweight and 37.7% of the population is in the heavier category of obese. The rate of obesity is a little higher for women than men; 40% of women are obese. The percentage of the population who are in the highest category of excess weight is also increasing. In fact, this most obese category more than doubled between 1990 and 2012 and represents 6.4% of the population.
What is Meant by “Overweight” and “Obese”?
The terms “overweight” and “obese” are often defined in medicine according to a calculation called the Body Mass Index (BMI). BMI is a measurement of body mass in terms of a person’s weight, divided by the square of their height. It is reported in kg/m2. Individuals are considered overweight if their BMI is 25 kg/m2 or higher and are considered obese if their BMI is 30 kg/m2 or higher. The full list of body mass categories based on BMI are:
How Does This Relate to Health Risks?
In terms of health risks associated with excess weight, the amount of body fat carried in the abdominal region is important. A high level of body fat in this area is called “central adiposity.” A measurement of the waist determines this diagnosis. The cutoff waist circumference measurements for being considered to have central adiposity are (assessed through measurements):
- ≥ 40 inches (102 cm) men
- ≥ 34.5 inches (88 cm) women
The metabolic changes associated with obesity, as well as the effects of the fat mass bearing down on the body and vital organs, result in a large number of comorbid diseases. The following seven diseases/conditions are most likely to co-occur with obesity:
- Cardiovascular disease
- Type 2 Diabetes mellitus/Prediabetes
- Sleep apnea
- Osteoarthritis and chronic pain syndromes, such as fibromyalgia, and problems of physical functioning
- Cancer: Breast, Cervical, Ovarian, Endometrial, Prostate, Thyroid, Colon, Rectal, Pancreatic, Biliary Tract, Gallbladder
(NCI, 2012; Mayo, 2014; NDIC, 2013).
Many other health problems are tied to obesity and often improve with weight loss.
Central adiposity, even more than BMI, is considered a predictor of certain health risks that are increased with obesity. For example, waist circumference is approximately twice as effective as BMI at predicting future coronary heart disease (Jensen, 2007). It is associated with greater risk for heart disease, stroke, and type 2 diabetes mellitus (Jensen et al., 2014). This increased risk is seen even with normal BMI.
Clearly, excess weight is a major health problem in the United States that deserves appropriate attention at the clinical and public health level.
- Flegal KM, Kruszon-Moran D, Carroll MD, Fryar CD, Ogden CL. Trends in Obesity Among Adults in the United States, 2005 to 2014. JAMA. 2016; 315(21): 2284-2291. Available at: http://jama.jamanetwork.com/article.aspx?articleid=2526639 Accessed on: 2016-06-08.
- Jensen MD. Should we measure waist circumference vs BMI vs waist-hip ratio. American Diabetes Association. Diabetes Pro. 2007; 54th Annual Post Graduate Course. Available at: http://professional.diabetes.org/search/site/Should%20we%20measure%20waist%20circumference%20vs%20BMI%20vs%20waist-hip%20ratio Accessed on: 2014-07-31.
- Jensen M, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Journal of the American College of Cardiology. 2014. Available at: http://circ.ahajournals.org/content/early/2013/11/11/01.cir.0000437739.71477.ee Accessed on: 2015-01-21.
- Mayo Clinic Staff. Coronary artery disease – Causes. Diseases and Conditions. 2014. Available at: http://www.mayoclinic.org/diseases-conditions/coronary-artery-disease/basics/causes/con-20032038Accessed on: 2014-06-19.
- National Cancer Institute. Obesity and Cancer Risk, NCI NIH. NCI. 2012. Available at: http://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/obesity-fact-sheet Accessed on: 2012-06-15.
- National Diabetes Information Clearinghouse (NDIC). Causes of Diabetes. NIDDK.gov. 2013. Available at: http://www.niddk.nih.gov/health-information/health-topics/Diabetes/causes-diabetes/Pages/index.aspx#Points Accessed on: 2014-02-11.