Breaking Free from BMI: Why It Doesn’t Work?

Last month, Zerodha co-founder Nithin Kamath, a fitness enthusiast, suffered a mild stroke. He linked the incident to various factors, including the recent loss of his father, inadequate sleep, fatigue, dehydration, and intense exercise. Last year Bollywood actress Sushmita Sen, also a fitness freak, survived a major heart attack. 

There is an increasing incidence of high blood pressure, diabetes and high cholesterol levels in the younger population. Can BMI accurately evaluate your health and indicate high cholesterol or diabetes? Does it provide a comprehensive insight into your physical condition?

Apart from classifying individuals as underweight, normal weight, overweight, or obese, is there any other purpose to BMI? 

Earlier, a BMI of 18.5 to 24.9 is categorised as Healthy Weight, while a BMI of 25.0 to 29.9 falls into the Overweight range. A BMI of 30.0 or higher is classified as Obese.

Remember, it doesn’t give you an accurate picture of your obesity or fitness levels like body weight. Celebrity nutritionist Rujuta Diwekar points out on her Instagram account. 

‘Body weight is not an indicator of fatness or fitness. It fluctuates with the time of the day and with age. It is possible to stay healthy and fit at any body weight.’

Don’t let a number fool you since many health professionals question its continued use as a singular indicator of health.

Still not convinced? 

Let’s first look at why it’s outdated.

The Flaws:

1. Ignoring Body Composition: BMI is solely based on weight and height, neglecting crucial factors like body composition. It doesn’t consider the person’s body fat against muscle (lean tissue) content. It overlooks other relevant elements, such as bone density or body water percentage. 
   
   For instance, a 6ft athlete with a high muscle mass can be wrongly classified as overweight or obese by solely relying on BMI, even though their body fat percentage might be within healthy ranges. His BMI might match that of an overweight person leading a sedentary lifestyle. 
   
   
   
   Notably, BMI is ineffective in distinguishing significant fat deposits in these organs, and overall body fat mass is a weak predictor of fat at these specific locations. 
   
   2. Erasing Ethnic and Racial Disparities: BMI calculations were derived from data on white males, potentially leading to inaccurate interpretations for other ethnicities and races. 
   
   Studies suggest that Asian populations tend to have a higher body fat percentage at a lower BMI compared to white populations, meaning they might be categorised as underweight despite having a healthy body composition. 
   
   Conversely, some Black individuals may be categorised as overweight based on their BMI, even with a lower body fat percentage. 
   
   3. Ignoring Age and Sex-Specific Considerations: BMI fails to consider the natural changes in body composition occurring throughout life, like a decrease in muscle mass, menopause, etc. Moreover, fat distribution varies between genders, with women typically having more body fat than men at the same BMI.  
   
   Additionally, muscle mass naturally decreases with age, particularly for women post-menopause. This could lead to older adults being wrongly categorised as underweight, even though their body fat percentage might be within the healthy range for their age and sex. 
   
   Due to these variations, BMI may not offer sufficient details to assess the quality of health in a person's weight. 
   
   4.Neglecting Individual Health Context: BMI doesn't account for individual health markers and lifestyle factors like diet, physical activity, and genetic predispositions. Individuals with a higher weight but consistent engagement in healthy behaviours might have a lower risk of chronic diseases compared to someone with a lower weight who engages in unhealthy habits.

      5. Never developed as a health marker: Conceived by 19th-century mathematician Lambert Adolphe Jacques Quetelet for a population census in the Netherlands, the BMI formula was originally a tool to estimate the typical sizes of the total population. 

Quetelet focused on mostly high-income white men to determine 'the ideal body weight' for resource distribution. 

In 1972, Ancel Keys and colleagues renamed the Quetelet index to BMI, proposing it as a quick, simple, and cost-effective measure of individual body fat. Its efficiency led to global government adoption in the 1980s for population health assessment.

Beyond the Number: A Comprehensive Approach to Health

So, instead of relying solely on the limitations of BMI, a more comprehensive approach to assessing individual health is crucial. This includes:

• Body composition analysis: Specially designed scales and handheld devices utilise bioelectrical resistance to send a small electrical wave through the body. This measures body composition, distinguishing between fat, water, and lean tissue with different currents. 
  Few methods like skinfold measurement, DEXA scan or bone density scan and Hydrostatic weighing provide an accurate picture of a person’s bone density, body fat, muscle mass and overall fitness level. 
• Waist circumference: Measuring waist circumference can offer insights into visceral fat, a specific type of fat associated with increased health risks. It better predicts adverse cardiovascular and metabolic outcomes of obesity than BMI.
• Blood pressure and cholesterol levels: Regularly monitoring these vital signs is crucial for assessing cardiovascular health risks.
• Dietary and physical activity assessments: Understanding an individual's dietary and physical activity patterns provides valuable insights into their overall health habits.
• Individual medical history and family history: Considering an individual's medical history and family history helps identify potential risk factors for specific health conditions.

By relying solely on BMI, we risk creating inaccurate perceptions of health and potentially fostering negative self-image and body shaming. 

Instead, focusing on a holistic approach that considers individual circumstances, lifestyle choices, and overall health markers empowers individuals to make informed decisions about their well-being, moving beyond the limitations of a single number. 

Long story short, your health status should fall within the green zone, indicating functional bodily movement and sufficient energy levels. BMI is not your marker for that.