We saw in a previous article that, while the World Health Organization (WHO) uses the Body Mass Index (BMI) to define obesity when the BMI exceeds 30 kg/m2, this parameter can be misleading, as some people above this threshold may have normal body fat (such as athletes with high muscle mass) and, conversely, others with a BMI below this threshold may have significant body fat.
On the other hand, many people with excess adipose tissue show no signs of disease.
So, while BMI is useful at the population level, its ability to predict health status at the individual level is more limited.
On the other hand, many people with excess adipose tissue show no signs of disease.
So, while BMI is useful at the population level, its ability to predict health status at the individual level is more limited.
Anthropometry is now preferred
Rather than using BMI alone to define obesity, anthropometric measurements of body fat are now used to diagnose obesity [1].
These measurements can be indirect (such as waist circumference, which reflects visceral fat mass within the abdominal cavity) or direct (such as biphotonic absorptiometry, which uses X-rays to measure the fat compartment).
Thus, for Caucasians, the diagnosis of obesity can now be made when a BMI greater than 30 kg/m2 is combined with a waist circumference ≥ 102 cm for men and ≥ 88 cm for women.
If the BMI is less than 30 kg/m2 or is unknown, the diagnosis of obesity can still be made by combining two of the following three anthropometric parameters:
Finally, independently of BMI and other simple clinical measurements, the diagnosis can be made by direct measurement of body fat (DEXA or CT scan, for example).
Thanks to these anthropometric measurements, muscular people with a high BMI but low body fat will not be wrongly diagnosed as obese.
These measurements can be indirect (such as waist circumference, which reflects visceral fat mass within the abdominal cavity) or direct (such as biphotonic absorptiometry, which uses X-rays to measure the fat compartment).
Thus, for Caucasians, the diagnosis of obesity can now be made when a BMI greater than 30 kg/m2 is combined with a waist circumference ≥ 102 cm for men and ≥ 88 cm for women.
If the BMI is less than 30 kg/m2 or is unknown, the diagnosis of obesity can still be made by combining two of the following three anthropometric parameters:
- Waist circumference ≥ 102 cm for men and ≥ 88 cm for women (for Caucasians)
- Waist/hip circumference ratio > 0.90 for men and > 0.85 for women
- Waist/height ratio > 0.50 for both men and women.
Finally, independently of BMI and other simple clinical measurements, the diagnosis can be made by direct measurement of body fat (DEXA or CT scan, for example).
Thanks to these anthropometric measurements, muscular people with a high BMI but low body fat will not be wrongly diagnosed as obese.
Pre-clinical or clinical obesity?
A diagnosis of obesity (excess body fat) does not, however, imply disease.
Indeed, while obesity is a risk factor for the development of diseases (cardiovascular, type 2 diabetes, etc.), not all obese people suffer from symptoms or illnesses linked to their obesity. They may even experience no discomfort in their daily activities. In this case, we speak of preclinical obesity.
If, on the other hand, there are limitations to daily activities, or symptoms or illnesses linked to obesity, we speak of clinical obesity. People suffering from clinical obesity have a variety of impairments, including :
It is important to ensure, however, that the symptoms/signs of organ dysfunction and/or reduced daily activities are consequences of obesity, if the diagnosis of clinical obesity is to be retained.
Indeed, while obesity is a risk factor for the development of diseases (cardiovascular, type 2 diabetes, etc.), not all obese people suffer from symptoms or illnesses linked to their obesity. They may even experience no discomfort in their daily activities. In this case, we speak of preclinical obesity.
If, on the other hand, there are limitations to daily activities, or symptoms or illnesses linked to obesity, we speak of clinical obesity. People suffering from clinical obesity have a variety of impairments, including :
- Shortness of breath due to the effects of obesity on the heart or lungs,
- Knee or hip pain accompanied by joint stiffness and reduced range of motion.
- A range of metabolic abnormalities (diabetes, etc.)
- Dysfunction of other organs, including the kidneys, upper respiratory tract, nervous, urinary and reproductive systems.
It is important to ensure, however, that the symptoms/signs of organ dysfunction and/or reduced daily activities are consequences of obesity, if the diagnosis of clinical obesity is to be retained.
What about you?
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