Obesity is a medical condition in which a high amount of body fat makes it hard for a person's internal organs to work well. This can cause poor health.
People with obesity have a higher chance of developing these health problems:
High blood glucose (sugar) or diabetes.
High blood pressure (hypertension).
High blood cholesterol and triglycerides (dyslipidemia or high blood fats).
Heart attacks due to coronary heart disease, heart failure, and stroke.
Bone and joint problems -- more weight puts pressure on the bones and joints. This can lead to osteoarthritis, a disease that causes joint pain and stiffness.
Stopping breathing during sleep (sleep apnea). This can cause daytime fatigue or sleepiness, poor attention, and problems at work.
Gallstones and liver problems.
Three things can be used to determine if a person's body fat gives them a higher chance of developing obesity-related diseases:
Body mass index (BMI)
Other risk factors the person has (A risk factor is anything that increases your chance of getting a disease.)
Body mass index
Body mass index (BMI) is calculated using height and weight. It is used to estimate body fat.
Starting at 25.0, the higher your BMI, the greater is your risk of developing obesity-related health problems. These ranges of BMI are used to describe levels of risk:
Overweight (not obese), if BMI is 25.0 - 29.9
Class 1 (low-risk) obesity, if BMI is 30.0 - 34.9
Class 2 (moderate-risk) obesity, if BMI is 35.0 - 39.9
Class 3 (high-risk) obesity, if BMI is equal to or greater than 40.0
Women with a waist size greater than 35 inches and men with a waist size greater than 40 inches have an increased risk of heart disease and type 2 diabetes. People with "apple-shaped" bodies (waist is bigger than the hips) also have an increased risk of these conditions.
Having a risk factor does not mean that you will get the disease. But it does increase the chance that you will. Some risk factors, like age, race, or family history cannot be changed.
The more risk factors you have, the more likely it is that you will develop the disease or health problem.
Your risk of health problems such as heart disease, stroke, and kidney problems increases if you are obese and have these risk factors:
High blood pressure (hypertension)
High blood cholesterol or triglycerides
High blood glucose (sugar), a sign of type 2 diabetes
These other risk factors for heart disease and stroke are not caused by obesity:
Having a family member under the age of 50 with heart disease
Being physically inactive or having a sedentary lifestyle
Smoking or using tobacco products of any kind
Summing it up
You can control many of these risk factors by changing your lifestyle. If you have obesity, your doctor can help you begin a weight-loss program. A starting goal of losing 5% - 10% of your current weight will reduce your risk of developing obesity-related diseases.
Screening for and Management of Obesity in Adults. Rockville, MD. US Preventive Services Task Force; June 2012: AHRQ publication 11-05159-EF-2.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial Team.