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Obesity

This guide provides reliable resources containing information on obesity, childhood obesity, and the health risks associated with obesity.

Introduction

Obesity is a chronic condition defined by an excess amount of body fat. It indicates a weight greater than what is considered healthy. 

Obesity has been more precisely defined by the National Institutes of Health (the NIH) as a BMI (Body Mass Index) of 30 and above. (A BMI of 30 is about 30 pounds overweight.) The BMI, a key index for relating body weight to height, is a person's weight in kilograms (kg) divided by their height in meters (m) squared.

MedicineNet

Decorative image: obesity sign.

Image Credit: picserver.org

The balance between calorie intake and energy expenditure determines a person's weight. If a person eats more calories than he or she burns (metabolizes), the person gains weight (the body will store the excess energy as fat). If a person eats fewer calories than he or she metabolizes, he or she will lose weight. Therefore, the most common causes of obesity are overeating and physical inactivity. Ultimately, body weight is the result of genetics, metabolism, environment, behavior, and culture.

  • Genetics. A person is more likely to develop obesity if one or both parents are obese. Genetics also affect hormones involved in fat regulation. 
  • Overeating. Overeating leads to weight gain, especially if the diet is high in fat. 
  • A diet high in simple carbohydrates. The role of carbohydrates in weight gain is not clear. Carbohydrates increase blood glucose levels, which in turn stimulate insulin release by the pancreas, and insulin promotes the growth of fat tissue and can cause weight gain. 
  • Frequency of eating. The relationship between frequency of eating (how often you eat) and weight is somewhat controversial. There are many reports of overweight people eating less often than people with normal weight. Scientists have observed that people who eat small meals four or five times daily, have lower cholesterol levels and lower and/or more stable blood sugar levels than people who eat less frequently. One possible explanation is that small frequent meals produce stable insulin levels, whereas large meals cause large spikes of insulin after meals.
  • Physical inactivity. Sedentary people burn fewer calories than people who are active. The National Health and Nutrition Examination Survey (NHANES) showed a strong correlations between physical inactivity and weight gain in both sexes.
  • Medications. Medications associated with weight gain include certain antidepressants, anticonvulsants, some diabetes medications, certain hormones such as oral contraceptives, and most corticosteroids. Some high blood pressure medications and antihistamines cause weight gain. 
  • Psychological factors. For some people, emotions influence eating habits. Many people eat excessively in response to emotions such as boredom, sadness, stress, or anger. 
  • Diseases such as hypothyroidism, insulin resistance, polycystic ovary syndrome, and Cushing's syndrome are also contributors to obesity.

MedicineNet

Excess weight may increase the risk for many health problems, including

  • type 2 diabetes
  • high blood pressure
  • heart disease and strokes
  • certain types of cancer
  • sleep apnea
  • osteoarthritis
  • fatty liver disease
  • kidney disease
  • pregnancy problems, such as high blood sugar during pregnancy, high blood pressure, and increased risk for cesarean delivery (C-section)

National Institute of Diabetes ad Digestive Kidney Diseases

 

In the United States, the percentage of children and adolescents affected by obesity has more than tripled since the 1970s. Data from 2015-2016 show that nearly 1 in 5 school age children and young people (6 to 19 years) in the United States has obesity.

Many factors contribute to childhood obesity, including:

  • Genetics
  • Metabolism—how your body changes food and oxygen into energy it can use.
  • Eating and physical activity behaviors.
  • Community and neighborhood design and safety.
  • Short sleep duration.
  • Negative childhood events

Genetic factors are difficult to change. However, people and places can play a role in helping children achieve and maintain a healthy weight. Changes in the environments where young people spend their time—like homes, schools, and community settings—can make it easier for youth to access nutritious foods and be physically active. Schools can adopt policies and practices that help young people eat more fruits and vegetables, eat fewer foods and beverages that are high in added sugars or solid fats, and increase daily minutes of physical activity.  These kinds of school-based and after-school programs and policies can be cost-effective and even cost-saving.

Centers for Disease Control and Prevention

There are countless weight-loss strategies available but many are ineffective and short-term, particularly for those who are morbidly obese. Among the morbidly obese, less than 5 percent succeed in losing a significant amount of weight and maintaining the weight loss with non-surgical programs — usually a combination of dieting, behavior modification therapy and exercise.

People do lose weight without surgery, however, particularly when they work with a certified health care professional to develop an effective and safe weight-loss program. Most health insurance companies don't cover weight-loss surgery unless you first make a serious effort to lose weight using non-surgical approaches.

Many people participate in a combination of the following therapies:

1. Dietary Modification

2. Behavior Modification

3. Exercise

4. Medications

5. Surgery

USFC Health

 

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Databases

eBooks + Books

Discover eBook collections or find print books/materials through the catalog for each campus:

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Suggested Websites

CDC-Centers for Disease Control and Prevention

Genomics and health.

The Endocrine Society

This site serves as the one-stop clearinghouse for the general public seeking information on the key scientific trends and advancements that may one day lead to a slimmer, fitter America.

 Mayo Clinic

Complications of Obesity

Obesity Society

Research. Education. Action.

The State of Obesity

National School Breakfast and Lunch Program: 70th Anniversary

 World Health Organization

General information on obesity and childhood obesity, including global strategy on diet, physical activity and health.

Eat Right

Academy of Nutritionist and Dietetics

Videos

A visual breakdown of why some individuals are resistant to maintaining weight loss through diet and exercise alone.