Overweight and Obesity
American society has become 'obesogenic,' characterized by environments that promote increased food intake, nonhealthful foods, and physical inactivity. Policy and environmental change initiatives that make healthy choices in nutrition and physical activity available, affordable, and easy will likely prove most effective in combating obesity.

The Division of Nutrition, Physical Activity, and Obesity (DNPAO) is working to reduce obesity and obesity-related conditions through state programs, technical assistance and training, leadership, surveillance and research, intervention development and evaluation, translation of practice-based evidence and research findings, and partnership development.

Defining Overweight and Obesity 
Overweight and obesity are both labels for ranges of weight that are greater than what is generally considered healthy for a given height. The terms also identify ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.

Definitions for Adults 
For adults, overweight and obesity ranges are determined by using weight and height to calculate a number called the "body mass index" (BMI). BMI is used because, for most people, it correlates with their amount of body fat.

An adult who has a BMI between 25 and 29.9 is considered overweight. 
An adult who has a BMI of 30 or higher is considered obese.

It is important to remember that although BMI correlates with the amount of body fat, BMI does not directly measure body fat. As a result, some people, such as athletes, may have a BMI that identifies them as overweight even though they do not have excess body fat. For more information about BMI, visit Body Mass Index.

Other methods of estimating body fat and body fat distribution include measurements of skinfold thickness and waist circumference, calculation of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic resonance imaging (MRI).

Definitions for Children and Teens
For children and teens, BMI ranges above a normal weight have different labels (overweight and obese). Additionally, BMI ranges for children and teens are defined so that they take into account normal differences in body fat between boys and girls and differences in body fat at various ages. For more information about BMI for children and teens (also called BMI-for-age), visit BMI for Children and Teens.

Assessing Health Risks Associated with Overweight and Obesity 
BMI is just one indicator of potential health risks associated with being overweight or obese. For assessing someone's likelihood of developing overweight- or obesity-related diseases, the National Heart, Lung, and Blood Institute guidelines recommend looking at two other predictors:

The individual's waist circumference (because abdominal fat is a predictor of risk for obesity-related diseases). 
Other risk factors the individual has for diseases and conditions associated with obesity (for example, high blood pressure or physical inactivity).

Causes and Consequences
Is there a quick answer to the question, "what contributes to overweight and obesity?"

Overall there are a variety of factors that play a role in obesity. This makes it a complex health issue to address. This section will address how behavior, environment, and genetic factors may have an effect in causing people to be overweight and obese.

The Caloric Balance Equation

• Overweight and obesity result from an energy imbalance. This involves eating too many calories and not getting enough physical activity. 
  
• Body weight is the result of genes, metabolism, behavior, environment, culture, and socioeconomic status. 
  
• Behavior and environment play a large role causing people to be overweight and obese. These are the greatest areas for prevention and treatment actions. 
  

When it comes to maintaining a healthy weight for a lifetime, the bottom line is – calories count! Weight management is all about balance – balancing the number of calories you consume with the number of calories your body uses or "burns off."

A calorie is defined as a unit of energy supplied by food. A calorie is a calorie regardless of its source. Whether you're eating carbohydrates, fats, sugars, or proteins, all of them contain calories.

Caloric balance is like a scale. To remain in balance and maintain your body weight, the calories consumed (from foods) must be balanced by the calories used (in normal body functions, daily activities, and exercise).

If you are... Your caloric balance status is...

Maintaining your weight "in balance."

• You are eating roughly the same number of calories that your body is using. Your weight will remain stable. 
  

Gaining weight "in caloric excess."

• You are eating more calories than your body is using. You will store these extra calories as fat and you'll gain weight. 
  

Losing weight "in caloric deficit."

• You are eating fewer calories than you are using. Your body is pulling from its fat storage cells for energy, so your weight is decreasing. 
  

Genetics and the environment may increase the risk of personal weight gain. However, the choices a person makes in eating and physical activity also contributes to overweight and obesity.

Environment
People may make decisions based on their environment or community. For example, a person may choose not to walk to the store or to work because of a lack of sidewalks. Communities, homes, and workplaces can all influence people's health decisions. Because of this influence, it is important to create environments in these locations that make it easier to engage in physical activity and to eat a healthy diet. The Surgeon General's Call to Action to Prevent and Decrease Overweight and Obesity 2001 identified action steps for several locations that may help prevent and decrease obesity and overweight. The following table provides some examples of these steps.

Steps to Help Prevent and Decrease Overweight and Obesity

Home

• Reduce time spent watching television and in other sedentary behaviors 
  
• Build physical activity into regular routines
  

Schools

• Ensure that the school breakfast and lunch programs meet nutrition standards 
  
• Provide food options that are low in fat, calories, and added sugars 
  
• Provide all children, from prekindergarten through grade 12, with quality daily physical education
  

Work

• Create more opportunities for physical activity at work sites
  

Community

• Promote healthier choices including at least 5 servings of fruits and vegetables a day, and reasonable portion sizes 
  
• Encourage the food industry to provide reasonable food and beverage portion sizes 
  
• Encourage food outlets to increase the availability of low-calorie, nutritious food items 
  
• Create opportunities for physical activity in communities
  

Genetics

How do genes affect obesity?
Science shows that genetics plays a role in obesity. Genes can directly cause obesity in disorders such as Bardet-Biedl syndrome and Prader-Willi syndrome.

However genes do not always predict future health. Genes and behavior may both be needed for a person to be overweight. In some cases multiple genes may increase one's susceptibility for obesity and require outside factors; such as abundant food supply or little physical activity.

Other Factors

Diseases and Drugs
Some illnesses may lead to obesity or weight gain. These may include Cushing's disease, and polycystic ovary syndrome. Drugs such as steroids and some antidepressants may also cause weight gain.

A doctor is the best source to tell you whether illnesses, medications, or psychological factors are contributing to weight gain or making weight loss hard.

For more information, visit: http://www.cdc.gov/obesity/