Written on April 14, 2023 by Sendra Yang, PharmD, MBA. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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Obesity is a common chronic condition with an expensive impact on the healthcare system . The prevalence of obesity continues to rise each year. Between 1975 and 2014, Global rates of obesity increased from 3.2% to 10.2% in men and from 6.4% to 14.9% in women . Worldwide estimates project that by 2025, 18% of men and 21% of women will be obese. In the United States, obesity prevalence from 1999 to 2020 increased from 30.5% to 41.9% .
Obesity is a costly disorder. The global financial burden of managing obesity and its complications is around $2 trillion annually . In the US, it is estimated that the annual medical expenses of obesity were about $172 billion in 2019 . Obese adults had approximately $1,860 higher medical costs when compared to people with a healthy weight.
Obesity not only impacts society because of increased healthcare spend but also impacts an individual's physical, mental, and social health .
Definition of obesity
According to the World Health Organization, obesity is defined as a health risk because of abnormal or excessive fat accumulation . The Centers for Disease Control and Prevention defines obesity as anyone with a body mass index (BMI) of 30 kg/m^2 or higher . BMI is a screening tool used to identify individuals who are overweight and obese. Obesity can be further subdivided into three classes :
- Class 1: BMI of 30 kg/m^2 to <35 kg/m^2
- Class 2: BMI of 35 kg/m^2 to <40 kg/m^2
- Class 3: BMI of 40 kg/m^2 or higher (known as severe obesity)
The complex mechanism of obesity
Obesity is a complex disease with various underlying mechanisms affecting the body . Two proposed mechanisms of obesity complications involve inflammation and the gut microbiome. Obesity leads to a state of constant low inflammatory response in organs such as the liver, brain, pancreas, and fat tissues. The activated immune cells and mediators cause a dysregulated immune system leading to metabolic and vascular complications.
The second proposed mechanism of obesity complications involves the gut microbiome . The microbiome is essentially the natural microbes or bacteria that live in your gut and contribute to your health and wellness . The gut microbiome impacts your metabolism by signaling pathways, effects of inflammation, fat deposits, and insulin resistance . Obesity is associated with changes in gut bacteria.
The underlying mechanisms of obesity contribute to systemic complications and affect multiple organs, leading to numerous comorbid conditions [2,3].
Comorbidities related to obesity
The risk of developing obesity-related comorbidities rises exponentially with increasing BMI over 30 kg/m^2, particularly in cardiovascular disease [2,6,7]. Obese people are at an increased risk for type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease, stroke, sleep apnea, gallbladder disease, gout, and osteoarthritis [2,7]. Certain cancers are associated with obesity, such as colorectal and pancreatic cancer in men and endometrial, breast, and gallbladder cancer in women [2,7]. Psychosocial comorbidities also exist with obesity, such as depression . Many of these comorbidities can improve with weight loss and management [2,3].
10 obesity-related comorbidities
- Type 2 diabetes: People with BMI over 35 kg/m^2 are almost 20 times more likely to develop type 2 diabetes than those with a normal BMI (18.5 to 24.9 kg/m^2) . A study of over 21,000 adults from the National Health and Nutrition Examination Survey found the risk of type 2 diabetes rises from 8% in people with normal weight to 43% in people with morbid obesity .
- Hypertension: As BMI increases for obese people, the blood pressure rises proportionately .
- Dyslipidemia: Approximately 70% of people with obesity also have dyslipidemia . Obesity affects cholesterol levels, raising LDLs, elevating triglycerides, and reducing HDLs [2,3].
- Heart disease: For every 4 kg/m^2 increase in the BMI, there is a reported 26% increase in the odds of coronary heart disease . Additionally, the risk of heart failure doubles in obesity. For each extra 1 kg/m^2 in BMI, the risk of heart failure increased by 5% in men and 7% in women. When comparing obese people to those with a BMI less than 23 kg/m^2, they are twice as likely to have a stroke.
- Gout: Obese men have two to three times the relative risk for gout compared to normal-weight individuals .
- Osteoarthritis: The most common joint affected by obesity is the knee, although the hand is at higher risk despite not being a weight-bearing joint .
- Obstructive sleep apnea (OSA): The prevalence of OSA in obese adults was 12% compared to 3% in lean people .
- Kidney disease: Obesity is associated with a higher risk of kidney stones and urinary incontinence in women, and the prevalence of kidney disease increases with obesity .
- Non-alcoholic fatty liver disease (NAFLD): The risk of NAFLD is strongly related to increased BMI . Rates of steatosis were 15% in non-obese people, 65% in Class 1 or 2 obesity, and 85% in Class 3 obese individuals.
- Certain cancers: Obesity accounts for around 20% of all cancer cases and was the cause of 25% to 33% of colon, breast, endometrium, kidney, and esophagus cancers [2,3]. Obese women with breast cancer were found to be 46% more likely to experience distant metastases and 38% more likely to die than those who are not overweight .
Benefits of weight loss
Losing weight, even a modest decrease of 5% to 10% of your total body weight, can yield many health benefits, including improvements in blood pressure, cholesterol levels, and blood sugars . Many comorbidities can improve with weight loss [2,3]. Talk to a healthcare professional if you are having challenges losing weight and are concerned about the various comorbidities. Through Everlywell, you can consult with a certified clinician via a telehealth weight loss visit from the comfort of your own home to discuss your weight loss goals. You can get monthly support from your healthcare provider to optimize your care plan and achieve your health targets.
What is comorbidity?
Managing obesity in patients with comorbidities: what to know
Comorbidities for weight loss surgery
- Adult obesity facts. Centers for Disease Control and Prevention. Published May 17, 2022. Accessed April 6, 2023. https://www.cdc.gov/obesity/data/adult.html
- Kinlen D, Cody D, O'Shea D. Complications of obesity. QJM. 2018;111(7):437-443. doi: 10.1093/qjmed/hcx152
- Lim Y, Boster J. Obesity and comorbid conditions. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023. https://www.ncbi.nlm.nih.gov/books/NBK574535/
- Defining adult overweight & obesity. Centers for Disease Control and Prevention. Published June 3, 2022. Accessed April 7, 2023. https://www.cdc.gov/obesity/basics/adult-defining.html
- Microbiome. National Institute of Environmental Health Sciences. Accessed April 7, 2023. https://www.niehs.nih.gov/health/topics/science/microbiome/index.cfm
- Kyrou I, Randeva HS, Tsigos C, Kaltsas G, Weickert MO. Clinical problems caused by obesity. In: Feingold KR, Anawalt B, Blackman MR, et al, editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000. https://www.ncbi.nlm.nih.gov/books/NBK278973/
- Khaodhiar L, McCowen KC, Blackburn GL. Obesity and its comorbid conditions. Clin Cornerstone. 1999;2(3):17-31. doi: 10.1016/s1098-3597(99)90002-9
- Nguyen NT, Nguyen XM, Lane J, Wang P. Relationship between obesity and diabetes in a US adult population: findings from the National Health and Nutrition Examination Survey, 1999-2006. Obes Surg. 2011;21(3):351-5. doi: 10.1007/s11695-010-0335-4
- Losing weight. Centers for Disease Control and Prevention. Published September 19, 2022. Accessed April 7, 2023. https://www.cdc.gov/healthyweight/losing_weight/