Is the Definition of Obesity Too Strict? Rethinking BMI Standards

The definition of obesity seems to be too strict?

The Department of Health defines the ideal BMI range as 18.5 to 24.
A BMI greater than 27 is classified as obesity.
However, why do you consider the standard for obesity to be around a BMI of 24?

Yú er, 30~39 year old female. Ask Date: 2007/07/24

Dr. Pan Yingda reply Physical Fitness

There is no specific reason; you could set it at 25, 26, or even 30.
I feel that Taiwan's criteria are quite lenient.
The WHO defines obesity as a BMI greater than 27, and the Asia-Pacific region once held a conference to set it at greater than 23.
I don't understand why Taiwan has established a threshold of 24; perhaps it's because if the threshold were set at 23, the number of obese individuals in Taiwan would significantly increase, which would not look good in terms of statistics, so they opted for 24 instead! (There may be other reasons or research supporting this decision.)
In Europe and the United States, the threshold of 27 was established based on research indicating that individuals with a BMI greater than 27 have a much higher risk of cardiovascular and other obesity-related diseases compared to those with a BMI below 27.
However, body types differ significantly between foreign populations and Asians, so when the BMI is set at 27, it loses its warning effect.
In other words, a BMI of 27 in Asians poses a greater risk than in Europeans or Americans.
Therefore, based on various research reports from different countries, the WHO Asia-Pacific region found that Asians with a BMI greater than 23 have a much higher likelihood of developing cardiovascular diseases, which is why they defined obesity as a BMI greater than 23.
This means that a BMI greater than 23 could have a significant impact on health.
I also don't understand the basis for Taiwan's threshold of 24.
Does setting it at 24 mean we can afford to be a bit heavier? After this explanation, do you still think the Department of Health's definition of obesity is too strict? Obesity defined by BMI is just one indicator; body fat percentage should also be considered.
A high BMI does not necessarily equate to a high risk; body shape must also be taken into account.

Reply Date: 2007/07/24

More Info

The definition of obesity and the standards set by health authorities, such as the BMI (Body Mass Index) classifications, have been a topic of considerable debate. The BMI is calculated by dividing a person's weight in kilograms by the square of their height in meters (kg/m²). According to the standards set by the Taiwan health authorities, a BMI of 18.5 to 24 is considered ideal, while a BMI greater than 27 is classified as obese. This classification has raised questions, particularly regarding the threshold of 24 for obesity in Taiwan, which seems to be more lenient compared to the World Health Organization (WHO) guidelines that define obesity as a BMI greater than 27, and the Asia-Pacific guidelines that set the threshold at 23.

One of the main arguments for the stricter standards in the Asia-Pacific region is the recognition that individuals of Asian descent may have different body composition and fat distribution compared to their Western counterparts. Research indicates that Asians tend to have a higher percentage of body fat at lower BMI levels, which correlates with an increased risk of obesity-related health issues, such as cardiovascular diseases and diabetes. Therefore, the WHO's recommendation to classify a BMI greater than 23 as obese for Asians is based on empirical evidence showing that health risks significantly increase at this lower threshold.

The question of why Taiwan has chosen a BMI of 24 as the cutoff for obesity could be attributed to various factors, including cultural perceptions of body image, public health policy considerations, and the potential impact on obesity statistics. A higher cutoff may result in fewer individuals being classified as obese, which could be seen as a more favorable public health outcome. However, this could also lead to complacency regarding the health risks associated with excess body fat.

It is important to note that BMI is just one indicator of health and does not account for factors such as muscle mass, fat distribution, and overall body composition. For instance, individuals who are muscular may have a high BMI but low body fat percentage, while others may fall within the normal BMI range yet have a high body fat percentage, particularly visceral fat, which is more harmful to health. This highlights the need for a more comprehensive assessment of health that includes body fat percentage and waist circumference measurements, which can provide a clearer picture of an individual's health status.

In conclusion, while the BMI standards set by health authorities serve as a useful guideline for assessing weight categories, they should not be the sole determinant of health. The definition of obesity may appear too strict or lenient depending on the cultural context and the population being assessed. It is crucial for health professionals and policymakers to consider a range of factors, including ethnicity, body composition, and individual health risks, when defining obesity and developing public health strategies. Ultimately, the goal should be to promote overall health and well-being rather than merely focusing on weight or BMI numbers.

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