Obesity is a disorder that involves having an excessive amount of body fat. Obesity increases the risk of other health problems, but dietary changes and physical activity can improve your health.

Obesity Overview

Reviewed: May 22, 2014

Obesity means having too much body fat. It is different from being overweight, which means weighing too much; the excess weight may come from muscle, bone, fat, and/or body water. Still, both terms mean that a person's weight is greater than what is considered healthy for his or her height. In the United States, more than 1 in 3 adults are considered obese.

Obesity occurs over time when you eat more calories than you use; your body stores the excess calories as fat. The balance between calories-in and calories-out differs for each person. Factors that might affect your weight include your genetic makeup, overeating, eating high-fat foods, and not being physically active.

Obesity is not just a cosmetic concern. Obesity increases the risk of diseases and health problems such as diabetes, heart disease, stroke, arthritis, and some cancers. However, even modest weight loss can improve or prevent the health problems associated with obesity. Dietary changes, increased physical activity, and lifestyle modifications can help you lose weight. Losing even 5 to 10 percent of your weight can delay or prevent the health problems associated with diabetes. Prescription medications and weight-loss surgery are additional options for treating obesity.

Obesity Symptoms

Obesity means having excess body fat. The weight and fat gain that lead to obesity usually happen over time. Some of the signs and symptoms of obesity include:

  • clothes feeling tight and needing a larger size
  • the scale showing that you have gained weight
  • having extra fat around the waist
  • having a higher than normal body mass index and waist circumference

Obesity Causes

Simply, obesity occurs when you consume more calories than you burn through exercise and normal daily activities. Your body stores these excess calories as fat.

Genetic, behavioral, and hormonal factors can influence body weight and metabolism, and obesity can sometimes be traced to a medical cause. However, such disorders are rare and, in general, the principal causes of obesity are:

  • inactivity. If you are sedentary, you can easily take in more calories every day than you use through exercise and normal daily activities.
  • unhealthy diet and eating habits. Weight gain is inevitable if you regularly eat more calories than you burn. Most Americans' diets are high in calories and are include fast food and high-calorie beverages.

Poor sleeping habits or lack of sleep can increase the risk of obesity, as can age, pregnancy, and smoking.

Obesity Diagnosis

Obesity is diagnosed when your body mass index (BMI) is 30 or higher. Your BMI is calculated by dividing your weight in kilograms (kg) by your height in meters (m) squared.

The following categories are used to define BMI in adults:

  • BMI below 18.5: underweight
  • BMI of 18.5-24.9: normal weight
  • BMI 25.0-29.9: overweight
  • BMI 30.0-39.9: obese
  • BMI 40.0 or higher: extremely obese

Living With Obesity

Obesity can be treated with several lifestyle strategies, which may be used in addition to a formal medical or treatment plan.

Learn about obesity. Education about obesity can help you learn more about why you became obese and what you can do about it. You may feel more empowered to take control and stick to your treatment plan. Read reputable self-help books and consider talking about them with your doctor or therapist.

Set realistic goals. When you have to lose a significant amount of weight, you may set goals that are unrealistic, such as trying to lose too much too fast. Instead, set daily or weekly goals for exercise and weight loss. Make small changes in your diet instead of attempting drastic changes that you are not likely to stick with for a long time.

Stick to your treatment plan. Changing a lifestyle you may have lived with for many years can be difficult. Be honest with your doctor, therapist, or other healthcare providers if you have trouble meeting your activity or dietary goals. You can work together to come up with new ideas or new approaches.

Enlist support. Get your family and friends on board with your weight-loss goals. Surround yourself with people who will support you and help you, not sabotage your efforts. Make sure they understand how important weight loss is to your health. You might also want to join a weight-loss support group.

Keep a record. Keep a food and activity log. This record can help you remain accountable for your eating and exercise habits. You can discover behavior that may be holding you back and, also, what works well for you. You may use your log to track other important health parameters such as blood pressure and cholesterol levels and overall fitness.

Identify and avoid food triggers. Distract yourself from your desire to eat with something positive, such as calling a friend. Practice saying “no” to unhealthy foods and big portions. Only eat when you are actually hungry.

Take your medications as directed. If you take weight-loss medications or medications to treat obesity-related conditions, such as high blood pressure or diabetes, take them exactly as prescribed. If you have a problem sticking with your medication regimen or have unpleasant side effects, talk to your doctor.

Obesity Treatments

The goal of obesity treatment is to reach and stay at a healthy weight. You may need to work with a team of health professionals to help you understand and make changes in your eating and activity habits.

The initial treatment goal is usually modest weight loss, usually 3% to 5% of your total weight. However, the more weight you lose, the greater the benefits.

All long-term, successful weight-loss programs require changes in your eating habits and increased physical activity. The treatment methods that are right for you depend on your level of obesity, your overall health, and your willingness to participate in your weight-loss plan.

Reducing calories and practicing healthier eating habits are vital to overcoming obesity. Although you may lose weight quickly at first, slow and steady weight loss over the long term is the safest way to lose weight and the best way to keep it off permanently.

Avoid drastic and unrealistic diet changes, such as crash diets, because they are unlikely to help you keep excess weight off for the long term.

The key to weight loss is reducing the number of calories you consume. You and your healthcare providers can review your typical eating and drinking habits to see how many calories you normally consume and where you can cut back. You and your doctor can decide how many calories you need to take in each day to lose weight, but a typical amount is 1,200 to 1,500 calories for women and 1,500 to 1,800 for men.

To make your overall diet healthier, eat more plant-based foods, such as fruits, vegetables and whole-grain carbohydrates. Also emphasize lean sources of protein such as beans, lentils, and soy and lean meats. Limit salt and added sugar and consume low-fat dairy products. Eat small amounts of fats, and make sure they come from heart-healthy sources, such as olive, canola, and nut oils.

Increased physical activity or exercise is essential to obesity treatment. Most people who are able to maintain their weight loss for more than a year get regular exercise, even simply walking.

People who are overweight or obese need to get at least 150 minutes a week of moderate-intensity physical activity to prevent further weight gain or to maintain the loss of a modest amount of weight. To achieve more significant weight loss, you may need to exercise 300 minutes or more a week. You probably will need to gradually increase the amount you exercise as your endurance and fitness improve.

Even though regular aerobic exercise is the most efficient way to burn calories and shed excess weight, any extra movement helps burn calories. Making simple changes throughout your day can add up to big benefits. Park farther from store entrances, do more household chores, garden, get up and move around periodically, and wear a pedometer to track how many steps you actually take over the course of a day.

A behavior modification program can help you make lifestyle changes and lose weight and keep it off. Steps to take include examining your current habits to find out what factors, stresses, or situations may have contributed to your obesity.

Everyone is different and has different obstacles to managing weight, such as a lack of time to exercise or late-night eating. Tailor your behavior changes to address your individual concerns.

Behavior modification, sometimes called behavior therapy, may include professional counseling and support groups.

In certain situations, prescription weight-loss medication may be needed to effectively treat obesity. Weight-loss medication is meant to be used along with diet, exercise, and behavior changes, not instead of them.

Commonly prescribed weight-loss medications include:

In some cases, weight-loss surgery, also called bariatric surgery, is an option for obesity treatment. Weight-loss surgery limits the amount of food you're able to comfortably eat or decreases the absorption of food and calories or both. While weight-loss surgery offers the best chance of losing the most weight, it can pose serious risks.

Vagal nerve blockade is another treatment for obesity. It involves implanting a device under the skin of the abdomen that sends intermittent electrical pulses to the abdominal vagus nerve, which tells the brain when the stomach feels empty or full. This new technology received FDA approval in 2014 for use by adults who have not been able to lose weight with a weight-loss program and who have a BMI of 35 to 45 with at least one obesity-related condition, such as type 2 diabetes.