Redefining Obesity

Reference: GS 3 – Achievements of Indians in science & technology

Why in the News?

  • A Commission of The Lancet journal has proposed redefining obesity.
  • The new definition looks beyond Body Mass Index (BMI) as the sole criterion.
  • It includes assessments of organ functioning and physical symptoms linked to obesity.
  • This approach aims to provide a more comprehensive understanding of obesity.

Redefining Obesity

Redefining Obesity: Key Highlights

  • The Lancet Diabetes & Endocrinology Commission has proposed a new definition and diagnostic method for obesity, moving beyond BMI, which calculates weight in relation to height.
  • Years of research and substantial evidence show that BMI alone is insufficient for diagnosing and treating obesity.
  • A separate publication introduced a new definition of obesity specifically tailored for Indians, aligning with the broader recommendations.
  • This development coincides with the availability of highly effective medicines, such as GLP-1 receptor agonists like Ozempic, to manage clinical obesity.

How Has Obesity Been Measured Thus Far?

  • The standard method worldwide relies on BMI (Body Mass Index) as the sole determinant of obesity.
  • BMI is calculated by dividing a person’s weight (in kilograms) by the square of their height (in meters).
  • Example: A person weighing 70 kg with a height of 1.75 m has a BMI of 22.86, which falls in the healthy range.

BMI categories:

  • Underweight: BMI < 18.5
  • Normal: BMI between 18.5 and 24.9
  • Overweight: BMI between 25 and 29.9
  • Obese: BMI ≥ 30 

Why Has the BMI-Based Method Been Criticized?

Over- and Under-Diagnosis:

  • People with excess body fat may not always have a BMI over 30 but still suffer health issues related to obesity.
  • Individuals with high muscle mass may have a BMI over 30 while being healthy and not requiring medical intervention.

Organ Function Variability:

  • Some people with excess body fat maintain normal organ function and require minimal or no medical intervention.

Limitations for Indians:

  • Many lean-looking Indians with a BMI below 30 have significant abdominal fat, which affects organ functioning.
  • Indians are more prone to diabetes, hypertension, and heart diseases at lower BMI levels due to higher body fat percentages and central obesity compared to Western populations.

Adjusted BMI Cut-Offs for Indians:

  • In 2009, BMI thresholds were revised for Indians:
    • Overweight: BMI 23–24.9
    • Obese: BMI ≥ 25
  • However, even this adjustment did not resolve the limitations of relying solely on BMI for diagnosing obesity.

The Lancet Commission’s New Proposed Definition of Obesity

Chronic Illness:

  • Obesity is defined as a chronic illness that alters organ functions, regardless of other coexisting conditions.
  • It can lead to life-altering or life-threatening complications.

Broader Diagnostic Criteria:

  • The new definition considers multiple physical parameters:
    • Height, weight, and waist circumference.
    • Muscle mass and functioning of various organs.

Comprehensive Symptom Assessment:

  • Physicians must evaluate signs and symptoms such as:
    • Breathlessness, wheezing, sleep apnea, and chronic fatigue.
    • High triglyceride levels, metabolic dysfunctions, and non-alcoholic fatty liver disease.
    • Changes in reproductive system function, heart failure, and joint pain.
  • A patient’s level of physical activity in daily life is also considered.

Physician-Driven Diagnosis:

  • Obesity cannot be self-diagnosed under the new definition.
  • A qualified physician must make the diagnosis, similar to other diseases and conditions.

What Does ‘Pre-Clinical Obesity’ Mean Under the New Definition?

Replacement of ‘Overweight’ Category:

  • The new definition eliminates the “overweight” category and introduces “pre-clinical obesity.”
  • This category describes individuals with excess body fat but no associated ongoing illness.

Characteristics:

  • It is considered a physical attribute, not an illness.
  • In some individuals, it may represent an early stage of clinical obesity.
  • In others, it could be a phenotype with a lower tendency to directly impact organ function.

Diagnosis:

  • Similar to clinical obesity, diagnosis requires meeting multiple physical parameters.
  • A physician assesses organ function to determine if pre-clinical obesity applies.

How Is Body Size Evaluated for This Definition?

  • Shift from Sole Reliance on BMI: While body size remains critical, BMI is no longer the sole determinant of body size or obesity.
  • Parameters for Evaluating Body Size: At least two of the following four measures are used:
  • BMI
  • Waist circumference
  • Waist-to-hip ratio
  • Waist-to-height ratio
  • Advanced Methods: Doctors may also use techniques like Dexa scans to directly measure body fat.

What Is Different About the New Definition for Indians?

Terminology: The Indian guidelines use “Stage 1” and “Stage 2” obesity classifications instead of “pre-clinical” and “clinical” obesity.

BMI as Entry Point:

  • BMI remains the initial diagnostic measure for obesity in India due to its familiarity and ease of implementation.
  • A BMI > 23 serves as the threshold for both Stage 1 and Stage 2 obesity.

Stage 1 Obesity:

  • BMI > 23, with optional consideration of waist circumference or waist-to-height ratio.
  • No symptoms indicating limitations in daily activities or chronic obesity-related conditions.

Stage 2 Obesity:

  • BMI > 23, plus at least one additional physical parameter (e.g., waist circumference or waist-to-height ratio).
  • Presence of obesity-associated limitations or comorbid conditions.

How Is Obesity to Be Treated?

Pre-Clinical (Stage 1) Obesity:

  • Focus on risk reduction and prevention of progression to clinical obesity.
  • Suggested interventions:
    • Counselling for weight loss and prevention of weight gain.
    • Lifestyle changes, including a healthy diet and regular exercise.
  • Regular monitoring is essential.

Clinical (Stage 2) Obesity:

  • Evidence-based, personalized interventions are recommended.
  • Treatment success should be measured by improvement in obesity-related symptoms rather than just weight loss.
  • Available options include:
    • New weight-loss medications (e.g., GLP-1 receptor agonists).
    • Weight-loss surgeries for selected patients.
    • Medicines should be prescribed judiciously, targeting those with symptoms or comorbidities rather than solely high BMI.

Source: The Indian Express

Mains question

Critically analyze the limitations of BMI as a measure of obesity and discuss how The Lancet Commission’s redefinition addresses these shortcomings, with special reference to the Indian context. (250 words)