DOCTOR'S VIEW ARCHIVE
In June of 1998, the National Heart, Lung, & Blood Institute of the National Institutes of Health (NIH) updated the guidelines for the definition and treatment of obesity.
The NIH guidelines no longer utilize the traditional height/weight charts for defining obesity that insurance companies have relied on for years. According to these new guidelines, assessment of overweight involves evaluation of three key measures-body mass index (BMI), waist circumference, and a patient's risk factors for diseases and conditions associated with obesity.
Below are listed some of the new guidelines. These guidelines present a new approach to the assessment of overweight and obesity and establish principles of safe and effective weight loss.
The body mass index (BMI) equals a person's weight in kilograms (kg) divided by their height in meters (m) squared. Since BMI describes body weight relative to height, it is strongly correlated with total body fat content in adults.
To estimate BMI using pounds and inches, use the weight in pounds (lb) divided by the height in inches (in) squared and multiply the result by 704.5.
"Overweight" is defined as a body mass index (BMI) value of 27.3 percent or more for women and 27.8 percent or more for men. These definitions of overweight are based on an analysis of BMI relative to the risks of disease and death.
"Obesity" is defined as a BMI of 30 and above. A BMI of 30 is about 30 pounds overweight. (Notably, some very muscular people may have a high BMI without health risks).
According to the NIH guidelines, the most successful strategies for weight loss include calorie reduction, increased physical activity, and behavior therapy designed to improve eating and exercise habits. Recommendations include:
- Engaging in moderate physical activity, progressing to 30 minutes or more on most or preferably all days of the week.
- Cutting back on dietary fat can help reduce calories and is heart-healthy. But reducing dietary fat alone- without reducing calories-will not produce weight loss.
- The initial goal of treatment should be to reduce body weight by about 10 percent from baseline (starting weight), an amount that reduces obesity-related risk factors.
- A reasonable time line for a 10 percent reduction in body weight is 6 months of treatment, with a weight loss of 1 to 2 pounds per week.
- Weight maintenance should be a priority after the first 6 months of weight-loss therapy.
- Patients should utilize lifestyle therapy for at least 6 months before considering drug therapy.
- In carefully selected patients (BMI >30 without additional risk factors or BMI >27 with two or more risk factors) who have been unable to lose weight or maintain weight loss with conventional nondrug therapies, weight- loss drugs approved by the FDA for long-term use may be tried as part of a comprehensive weight loss program that includes dietary therapy and physical activity.
- During the weight maintenance phase of treatment, drug therapy may also be used. However, drug safety and effectiveness beyond one year of total treatment have not been established.
- Weight-loss surgery is an option for carefully selected patients with clinically very severe obesity-BMI of > 40 or BMI of >35 with coexisting conditions when less invasive methods have failed and the patient is at high risk for obesity-associated illness. Lifelong medical surveillance after surgery is a necessity.
- Overweight and obese patients who do not wish to lose weight, or are otherwise not candidates for weight loss treatment, should be counseled on strategies to avoid further weight gain.
- Age alone should not preclude weight loss treatment in older adults.
This information should be used as a compliment to MedicineNet's article on the topic which can be found in the Obesity Center.
You can calculate your own BMI by reading the MedicineNet.com article, Calculate Your BMI.