Health Guide » 
Overview
What is obesity?
Many people are concerned about their weight. Society emphasizes being thin, and heavier people often are very aware of their weight and how they are seen by others. We hear in the news that more and more people are becoming overweight and obese—but what does this mean?
Obesity means having too much body fat (adipose tissue). Obesity generally is determined by calculating your body mass index (BMI), which measures weight for height and is stated in numbers. BMI is not about how you look but rather an indication of the effect your weight has on your health. If you have too much weight for your height, you are at risk for developing health problems, such as type 2 diabetes.
A BMI of 30 or higher is considered obese in adults—you are at a higher risk for certain health problems than those with a lower BMI. As BMI increases, your risk of health problems increases.
Obesity is considered a long-term, complex disease. Many factors are involved in determining why some people are heavier than others and how much risk they have for developing other health conditions. Some of these factors are genetic (you have inherited them) and others have to do with your culture, environment, and behavior.
If your BMI is between 25 and 30, you are considered overweight (and also at increased risk for certain diseases). For information on maintaining a healthy weight, see the topic Healthy Weight.
What causes obesity?
You gain weight when you consume more calories from food than your body uses through its normal functions (basal metabolic rate [BMR]) and physical activity. The unused calories are stored as fat. You become obese if you consistently consume excess calories over a long period of time. For example, eating an extra 100 calories per day (less than half a turkey sandwich) can lead to a gain of about 10 lb(4.5 kg) in a year. Gaining 10 pounds a year eventually will result in a BMI of 30 or higher.
However, calories alone do not explain weight gain and why some people gain (or lose) weight more easily than others. Other factors that play a major role in weight gain and obesity include:
- Genetics. If either of your parents were obese, you are more likely to be obese.
Eating behavior. A diet high in fat and low in fruits and vegetables may lead to weight gain and obesity. - Your activity level. Activity uses calories, which helps balance the calories you get through food. If you are inactive, it may be easier to gain weight.
- Your environment. Being part of a culture that has readily available, inexpensive food and that emphasizes high-fat foods and large portions can lead to more calories and more weight.
What health problems does obesity put me at risk for?
According to the U.S. National Institutes of Health, all people age 18 or older who have a BMI of 25 or higher are considered at risk for disease and early death because of being overweight or obese.1
If you are obese, you are more likely to develop type 2 diabetes, high blood pressure, coronary artery disease (CAD), stroke, and sleep apnea, among other conditions. If you lose weight, your risk for these conditions is reduced.
Often overlooked are the psychological and cultural problems associated with being obese. Stereotypes of obese people—such as that they are lazy—and the emphasis our society places on thinness may result in low self-esteem, a poor body image, depression, and eating disorders. Stereotypes also may make it more difficult for an obese person to find a job or to progress in one.
How is obesity diagnosed?
Your health professional will take your medical and family history, do a physical examination, and use your BMI to determine whether you are obese.
- Healthy weight (BMI) chart for adults
- Healthy weight (BMI) chart for adults (metric)
- Your health professional may measure your waist or determine your waist-to-hip ratio (WHR) to determine how excess fat is distributed on your body. The location of body fat helps determine your risk for other health problems.
If your weight or family history suggests you have an increased risk for developing related health problems, your health professional may want to do more tests. The most common tests are for high blood pressure and blood tests to check for type 2 diabetes, high cholesterol or triglycerides, and thyroid problems.
How is obesity treated?
Because obesity is a chronic disease, it requires long-term management. Treatment focuses on losing weight to improve or eliminate related health problems or the risk for health problems, not to attain an ideal weight. Treatment consists of modifying your eating behaviors, physical activity, and monitoring your behavior, such as tracking what triggers you to eat. Medication and surgery may be used if this treatment is not effective.
Treatment also covers the psychological and social components of obesity. Stress management and counseling may be helpful. Getting family support and creating community contacts help you deal with the stereotypes and other social issues that are associated with obesity.
