What are the measures of obesity, including body mass index (BMI)?

From the Guidelines

Obesity is most accurately and practically measured using a combination of Body Mass Index (BMI) and waist circumference, with BMI calculated as weight in kilograms divided by height in meters squared, and waist circumference thresholds of over 40 inches (102 cm) for men and over 35 inches (88 cm) for women indicating increased health risks. According to the most recent and highest quality study 1, BMI is widely used to diagnose and stage obesity, with categories including overweight (BMI 25–29.9 kg/m2), obesity class I (BMI 30–34.9 kg/m2), obesity class II (BMI 35–39.9 kg/m2), and obesity class III (BMI ≥40 kg/m2). However, it is emphasized that BMI should not be relied on as a sole diagnostic and staging tool due to its limitations in distinguishing between fat and muscle mass.

Key points to consider in measuring obesity include:

• Using BMI as a routine measure for diagnosis, as recommended by guidelines from high-income countries 1.
• Considering waist circumference as an additional measure to assess the risk of developing obesity-related long-term health problems, with thresholds as mentioned 1.
• Recognizing the importance of a multifactorial, comprehensive lifestyle intervention that includes reduction in calorie intake, increase in physical activity, and measures to support behavioral change, as essential in the treatment of overweight and obesity 1.
• Understanding that pharmacological weight reduction and bariatric surgery may be considered as adjuncts to lifestyle interventions under specific conditions 1.

In clinical practice, combining BMI with waist circumference provides a practical approach to assess obesity-related health risks in most patients, taking into account the limitations of each measure and the need for a comprehensive assessment of health risks associated with obesity 1.

From the FDA Drug Label

to see if orlistat capsules are right for you, find your height on the chart to the right You may consider starting a weight loss program with orlistat if your weight is the same or more than the weight shown for your height. Ht. / Wt. 4’10” 129 lbs. 4’11” 133 lbs. 5’0” 138 lbs. 5’1” 143 lbs 5’2” 147 lbs. 5’3” 152 lbs. 5’4” 157 lbs. 5’5” 162 lbs. 5’6” 167 lbs. 5’7” 172 lbs. 5’8” 177 lbs. 5’9” 182 lbs. 5’10” 188 lbs. 5’11” 193 lbs. 6’0” 199 lbs. 6’1” 204 lbs. 6’2” 210 lbs. 6’3” 216 lbs. 6’4” 221 lbs. 6’5” 227 lbs. The measures of obesity for considering the use of orlistat include:

• Height and Weight: The drug label provides a chart with height and corresponding weight values to determine if orlistat is right for the patient.
• Weight Status: Patients may consider starting a weight loss program with orlistat if their weight is the same or more than the weight shown for their height on the chart 2.

From the Research

Measures of Obesity

• There are several methods used to measure obesity, including body mass index (BMI), waist-to-hip ratio (WHR), lean body mass, and more advanced techniques such as densitometry and dual-energy x-ray absorptiometry (DEXA) 3.
• BMI is a commonly used metric to define anthropometric height/weight characteristics in adults and to classify them into groups, but it has been shown to be a poor indicator of percent body fat 4.
• The World Health Organization defines cut-off values for obesity based on BMI, with a BMI of 25 kg/m2 or higher considered overweight and 30 kg/m2 or higher considered obese 5.
• However, the relationship between body fat percentage and BMI differs between ethnic groups, and cut-off points for overweight and obesity based on BMI may need to be ethnicity-specific 5.
• Other methods, such as measuring lean body mass and percent body fat, can provide more accurate assessments of obesity, but may be more expensive and time-consuming to use in large-scale studies 3, 6.
• Leptin levels have also been shown to be a reliable indicator of body fat, and can be used to enhance the accuracy of BMI estimates of percentage body fat 6.

Limitations of Current Measures

• BMI has several limitations, including its inability to capture information on the mass of fat in different body sites, which can be related to health issues 4.
• BMI can also misclassify individuals as non-obese when they are actually obese, particularly in women with high leptin levels 6.
• The use of BMI as a sole measure of obesity can lead to underestimation of the prevalence of obesity, especially in women 6.

Alternative Measures

• Dual-energy x-ray absorptiometry (DEXA) is a more accurate method of measuring body fat, but may be more expensive and time-consuming to use in large-scale studies 3, 6.
• Leptin levels can be used as a biomarker to enhance the accuracy of BMI estimates of percentage body fat, particularly in women with high leptin levels 6.
• Other methods, such as bioelectrical impedance analysis, can also be used to measure body fat, but may have their own limitations and biases 3.