A diagnosis of obesity can come from calculating body mass index (BMI). A BMI of 30 or more is considered obese.

Waist-to-hip ratio divides the circumference of the waist by the circumference of the hips. A high ratio reveals central obesity.

A physician determines whether or not someone is clinically obese – and therefore at an increased risk for the development of type 2 diabetes and other diseases. It is likely that in addition to measuring a patient’s BMI and waist circumference, a patient’s medical history will be reviewed to take into consideration other risk factors, including smoking, drinking alcohol and high levels of stress.

Patients with diabetes, including type 1 diabetes and gestational diabetes, can often achieve better control of their glucose (blood sugar) levels by losing excess weight, becoming more active and following a healthy eating plan.

Even losing as little as 5 to 7 percent of body weight can result in a dramatic decrease in risk for diabetes, heart disease and stroke. Most physicians agree that management and treatment of obesity requires permanent changes to the diet. To lose weight, numerous options are available, including:

• Good nutrition. For most people, a balanced diet containing no more than 2,000 calories a day for women and 2,500 for men is recommended. Crash diets are not recommended as they can lead to additional health problems.
  
  
• Regular exercise. Exercise without an associated change in diet will likely reduce weight by only a few pounds. Physical exercise of at least 150 minutes a week along with a balanced diet is crucial for long-term weight loss. For those already diagnosed with diabetes, exercise has also been proven to reduce the risk of developing complications, including coronary artery disease.
  
  
• Nutrition counseling. Several studies have confirmed that obese patients who receive nutritional counseling from a dietitian achieved better weight-loss outcomes, including better metabolic control and reduced waist circumferences.
  
  
• Diet pills. Some diet pills are available over the counter, and others require a physician's prescription. The U.S. Food and Drug Administration has approved only one over-the-counter weight-loss drug, a form of orlistat known as Alli. The usefuless of many of the other nonprescription substances marketed as weight-loss aids has not been proven, and there may be concerns about side effects and safety. Anyone considering use of these drugs should discuss the potential risks with a physician. It is also important to eat right and exercise regularly.

Prescription diet pills may be recommended for some patients. However, most people who use them regain the weight when they stop taking the medication. Also, the long-term effects of taking these drugs are not known. Research is continuing on improved weight-loss medications.

• Gastric surgery. In cases of morbid obesity (BMI greater than 40), doctors may recommend gastroplasty (stomach stapling) or gastric bypass. These bariatric operations allow limited amounts of food to be eaten at one time. There have been reports of bariatric surgery resolving some cases of type 2 diabetes, but it is important to note that these procedures carry risks and can have considerable side effects.

For people who take medication for type 2 diabetes, some newer antidiabetic agents may be an option. A recently introduced class of injected medications called incretin mimetics has helped many patients lose weight.