Obesity as a risk factor for chronic diseases

Obesity is one of the most common disorders in medical practice. In the United States about 60 million people are now obese (more than 30%) and 68% of population is overweight.  It is alarming that overweight rates among children have doubled and among adolescents even tripled, increasing the number of years they are exposed to the health risks of obesity. Obesity is defined as an excess of body fat. The best way to classify obesity is to use body mass index (BMI). It closely correlates with excess fat tissue, and it’s calculated by dividing measured body weight in kilograms by the height in meters squared.  A normal BMI is defined as 18.5 – 24.9. Overweight is defined as BMI 25-29, 9 and obesity is BMI over 30. Class I obesity is 30-34.9, class II obesity 35-39, 9 and extreme obesity, or class III is over 40. Obesity is a risk factor for developing type 2 diabetes, cardiovascular diseases, especially coronary disease, hypertension, obstructive sleep apnea , knee osteoarthritis, hyperlipidemia (high blood cholesterol levels) and even cancer.  It is also an important risk factor for stroke, abdominal angina, obesity hypoventilation syndrome (Pickwickian syndrome) and deep vein thrombosis (which is a risk factor for developing pulmonary embolism).  For example, except the fact that diabetes is the risk factor for developing coronary disease it is also the leading cause of amputation of the lower limbs throughout the world.

The main cause of obesity in the most of cases is sedentary life and chronic ingestion of excess calories. But, nowadays, it has been discovered that genetic influences are very important, to even 40-70 %. Most probably is that obesity develops from the interactions of multiple genes, environmental factors and behavior. Since there is a rapid increase in obesity in the last 30 years it is obvious that environmental factors have the most important role in the development of this disease. Upper body obesity (excess fat around waist and flank) is much more dangerous than lower body obesity (fat in the thighs and buttocks) and it is a greater risk for developing diabetes mellitus, stroke, coronary artery disease and early death. Of course, it is important to know  that obesity itself leads to hyperlipidemia, which leads to atherosclerosis, and that’s the most important risk factor for developing cardiovascular and cerebrovascular disease, and they are the leading cause of death in the Western World. Of course atherosclerosis will develop even if people have low cholesterol levels and if they are slim, but the process will be slower and the stenosis of the arteries probably won’t be significant.  Also, some studies have shown that being only 10 pounds overweight increases the force on the knee by 30-60 pounds with each step. Overweight women have nearly 4 times the risk of knee osteoarthritis; for overweight men the risk is 5 times greater. For a woman of normal height, for every 11 lb weight loss (approximately 2 BMI units), the risk of knee osteoarthritis dropped > 50%. Conversely, a comparable weight gain was associated with an increased risk of later developing knee OA. It is obvious that obesity plays an important role in the development of the most important chronic diseases today and by controlling our weight we can significantly decrease the risk of sudden and early death as well as the disability caused by stroke, heart attack, osteoarthritis or diabetes.


1. Role of Body Weight in osteoarthritis, http://www.hopkinsarthritis.org/patient-corner/disease-management/role-of-body-weight-in-osteoarthritis/

2. Maxine A.Papadakis, Current Medical Diagnosis and Treatment 2014, Visceral Artery Insufficiency (Intestinal Angina), p 453-454

3. Diabetes and Amputation, http://www.diabetes.co.uk/diabetes-and-amputation.html

4. Kumar and Clark, Clinical Medicine, 2005, 6th edition, Obesity p.252-257

5.Robert B.Baron, MD, MS, Nutritional Disorders, Obesity, , Current Medical Diagnosis and Treatment 2014, 53rd edition p.1213-1215

6. Robert F.Kushner, Evaluation and Management of Obesity, Harrison’s Principles of Internal Medicine (18th edition), p 629-634

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