Diseases Related to Obesity

Why Is Obesity a Disease?

Obesity is the most common chronic disease in the United States. Currently, nearly 40% of the U.S. adult population suffers from obesity. This number is expected to reach 50% in less than 15 years. Lifespan is shortened by 2-4 years in those with a body mass index (BMI) greater than 30 kg/m2 and 8-10 years in those with a BMI greater than 40 kg/m2. The latter is comparable to the effects of smoking.

Obesity is associated with an increased risk of many common medical conditions and resultant poor health. Diseases related to obesity include diabetes, sleep apnea, and fatty liver disease, which often occur in individuals who are not at a healthy weight for their body type.

Many organ systems are affected by excess weight because of either physical or metabolic stress caused to the body. Diseases related to obesity can generally be divided into two broad interrelated categories: biomechanical and metabolic.

Biomechanical stress from obesity can result in many common physical complaints seen in primary care, including arthritis, low back pain, plantar fasciitis, hernias, and varicose veins. Excess wear and tear to the knee and hip joints from carrying extra weight may lead to the breakdown of cartilage over time and subsequent need for joint replacement. Sleep apnea and reflux are predominantly seen in those who suffer from obesity due to the biomechanical forces from increased weight pushing against the chest and diaphragm and collapse of soft tissues of the neck during sleep.

It is now recognized that adipose tissue is an organ that secretes hormones affecting endocrine and immune function. As fat cells enlarge beyond their normal capability, the body stores energy in the form of fat where it does not belong (seen in fatty liver), or preferentially around the waist. This is called adiposopathy or “sick fat.” When this happens, metabolic diseases, such as diabetes, can occur, as well as worsening high blood pressure and elevated cholesterol. Though these are the most common metabolic diseases related to obesity, there are many others, including gall bladder disease, gout, polycystic ovaries, heart disease, cataracts, and many cancers, including breast, prostate, colon, and esophageal cancer.

Improving physical health through weight loss improves obesity-related conditions. Obesity medicine specialists have the knowledge and training to directly address the chronic disease of obesity. When an obesity-centric approach is taken to treat excess weight, many of the diseases related to obesity can be reduced, eliminated, or avoided.


This article was written by Lydia Alexander, MD, FOMA. Dr. Alexander is an internal medicine and obesity medicine physician at Kaiser Permanente in San Francisco.