Obesity is a complex disorder involving an excessive amount of body fat that increases your risk of many health problems, including heart disease, diabetes and high blood pressure.

You’re considered obese when your body mass index (BMI) is 30 or higher. Your body mass index is calculated by dividing your weight in kilograms (kg) by your height in meters (m) squared. For most people, BMI is a reasonable estimate of body fat. But some people, such as muscular athletes, may have a BMI in the obese category even though they don’t have excess body fat.


Although there are genetic and hormonal influences on body weight, obesity typically occurs when you take in more calories than you burn through exercise and normal daily activities. Obesity usually results from a combination of factors. Some of the more common factors include:

  • Inactivity. If you’re not very active, you don’t burn as many calories. With a sedentary lifestyle, you can easily take in more calories every day than you use through normal daily activities.
  • Unhealthy diet. You’re more likely to be obese if your diet is high in calories, lacks fruits and vegetables, includes a lot of fast food, and is laden with high-calorie beverages and oversized portions. All contribute to weight gain.
  • Lack of sleep. Too little sleep can cause changes in hormones that increase your appetite. You may also crave foods high in calories and carbohydrates, which can contribute to weight gain.
  • Certain medications. Some medications are associated with weight gain. They include some antidepressants, anti-seizure medications, diabetes medications, antipsychotic medications, corticosteroids, and beta-blockers.
  • Medical problems. Obesity can sometimes be traced to a medical cause, such as Prader-Willi syndrome or Cushing’s syndrome. Some medical problems, such as arthritis, can lead to decreased activity, which may result in weight gain.
  • Genetics. Your genes may affect the amount of body fat you store and where that fat is distributed. Genetics may also play a role in how efficiently your body converts food into energy and how your body burns calories during exercise. Even if you have a genetic predisposition, environmental factors ultimately make you gain more weight.


The goal of treatment is to reach and stay at a healthy weight. Weight-loss therapies include:
Dietary changes
Reducing calories and eating healthy foods are vital to overcoming obesity. Slow and steady weight loss over the long term is considered the safest way to lose weight and the best way to keep it off. Avoid drastic and unrealistic diet changes, such as crash diets. You and your doctor can determine how many calories should consume 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.

Exercise and activity
People who are able to lose weight and maintain their weight loss for more than a year generally get regular exercise. Aim for at least 150 minutes a week of moderate-intensity physical activity. To achieve more significant weight loss, you may need to exercise 300 or more minutes a week.

Behavior changes
A behavior modification program examines your habits to find out what factors, stresses, or situations may have contributed to your obesity and helps you make changes. Therapy can take place on both an individual and a group basis.


Weight-loss surgery can help you lose as much as 35 percent or more of your excess body weight, but surgery isn’t a miracle cure. To keep the weight off, you still need to make lifestyle changes. Weight-loss surgeries include:

  • Gastric bypass surgery. A surgeon creates a small pouch at the top of your stomach. The small intestine is cut a short distance below the main stomach and connected to the new pouch. Food and liquid flow directly from the pouch into the small intestine, bypassing most of your stomach.
  • Laparoscopic adjustable gastric banding (LAGB). Your stomach is separated into two pouches with an inflatable band. Pulling the band tight, like a belt, the surgeon creates a tiny channel between the two pouches. The band keeps the opening from expanding. LAGB is popular because it’s less invasive than other procedures, but the results aren’t as good.
  • Gastric sleeve. Part of the stomach is removed, creating a smaller reservoir for food. Ongoing studies are evaluating this procedure.
  • Biliopancreatic diversion with duodenal switch. In this procedure, most of your stomach is surgically removed. It’s generally used in people who have a body mass index of 50 or more.

            Excerpt From: The Mayo Clinic. “Mayo Clinic A to Z Health Guide”.