Health risks of obesity

Obesity is a medical condition in which a high amount of body makes it hard for a person’s internal organs to work well. This can cause poor health.

People with obesity are at risk for 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

These three things can be used to determine if a person’s body fat puts them at risk for developing obesity-related diseases:

  • Body mass index (BMI)
  • Waist size
  • Other risk factors the person has

Body Mass Index

Body mass index (BMI) is calculated using height and weight. It is used to estimate body fat. Link to BMI calculator.

In general, starting at 25.0, the higher your BMI, the greater is your risk for 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 - 34.9
  • Class 2 (moderate-risk) obesity, if BMI is 35 - 39.9
  • Class 3 (high-risk) obesity, if BMI is equal to or greater than 40

Waist Size

Women with a waist size greater than 35 inches and men with a waist size greater than 40 inches have an increased risk for heart disease and type 2 diabetes. People with "apple-shaped" bodies (meaning their waist is bigger than their hips) also have an increased risk for these conditions.

Risk Factors

A risk factor is anything that increases your chance of getting a disease.

Having a risk factor does not mean that you will get the disease, but it increases the chance you will. Some risk factors, like a person's age, race, or family history cannot be changed.

In general, the more risk factors you have, the more likely 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 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 most of these risk factors by changing your lifestyle. If you have obesity, your health care provider can help you begin a weight-loss program with a starting goal of losing 5 - 10% of your current weight. This will reduce your risk of developing obesity-related diseases.

Update Date: 7/1/2011

Updated by: 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, Medical Director, A.D.A.M., Inc.


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