Reliability of BMI as an index for fattiness and obesity in active population in comparison to Endomorphy component as an index

Aim: The aim of the present study was to find out whether BMI is a reliable index for fattiness and obesity compare to endomorphy component as index. Methods: 439 males and 475 females from different countries across the world were measured over an extended period of years to 2020 for . Stretched stature, Body weight, Skinfold Thicknesses (Biceps, Triceps, Supraspinale and Calf), Girths (Arm Flexed and Tensed and Calf) and Biepicondylar breadth ( Humerus and Femur). Results: Very low correlation (r = 0.18) was observed between BMI and fat % whereas high correlation ( r = 0.61, p< .05) was observed between BMI and Fat Free Mass ( FFM). correlation coefficient ( r) between BMI and Mesomorphy component was 0.79 ( p<.05). Correlation coefficient ( r) between Endomorphy and fat % was 0.86(p<.05). Conclusion: Thus from the above study, it can be concluded that, for individuals, BMI is more associated with muscularity than it is with fatness.


Introduction
Body Mass Index (BMI) is a simple anthropometrical method to classify the human body according to its nutritional status in terms of degree of fattiness and obesity. The basis of Body Mass Index (BMI) was the Quetelet index, which was first introduced by Lambert Adolphe Jacques Quetelet (1830-1850) as a simple measure to classify body weight relative to an ideal for height (Eknoyan 2008). Later on, Body Mass index (BMI) became a simple index of weight-for-height that is commonly used to classify overweightness and obesity in adults Overweightness and obesity are defined as excessive fat accumulation in the body. A body mass index (BMI) over 25 is considered overweight, and over 30 is obese. Obesity has turned into an epidemic over the last few decades irrespective of whether a country is developed or developing. According to the Global Burden of Disease, over 4 million people die every year as a result of being either overweight or obese (WHO 2017). Though BMI has been regarded as a reliable index of health for the last 170 years, it may not be an accurate predictor because BMI does not distinguish between muscle and fat, nor between body lean mass and body fat mass. This can lead to confusion and misinformation about fattiness and obesity (Strain GW, Zumof 1992, Wellens et al. 1996, Flegal et al. 2009, Nuttal 2015. The Endomorphy component describes the fattiness of a person as a part of a three-component Somatotype that describes the shape and size of the human body. Other two components of somatotype are mesomorphy and ectomorphy where mesomorphy indicates the muscularity and ectomoprhy describes the linearity (Carter and Heath 1990).
The aim of the present study was to find out whether BMI is a reliable index for fattiness and obesity compare to endomorphy component

Participants:
439 males and 475females from different countries across the world were measured over an extended period of years to 2020. At the time of measurement, all participants were physically active at their profession which had to involve significant physical labour, e.g. farming, hunting, professional sport and personal training.

Anthropometric measurements:
Stretched stature, Body weight, Skinfold Thicknesses (Biceps, Triceps, Supraspinale and Calf), Girths (Arm Flexed and Tensed and Calf) and Bi-epicondylar breadth ( Humerus and Femur) were measured by an ISAK Criterion Anthropometrist according to the methods described in ISAK Manuals (International Standards for Anthropometric Assessment), 2011 and 2019 editions.

Body Mass Index(BMI)
Body Mass Index (BMI) was calculated using the equation where BMI = Weight (kg) / Height(m)2.
Body Fat %: Body fat % was calculated using the equation of Siri (1956).
The Durnin and Womersley (1974) calculation was followed for Body density.
Statistical analysis: The SPSS 15 (IBM SPSS Statistics) software package was used for statistical analysis.

Discussion
In the present study, correlation between BMI and fat % was very low (r = 0.18). On the other hand, relationship between BMI and Fat Free Mass ( FM) was significantly (r = 0.61, p< .05). This was also reflected when the relationship between BMI and Mesomorphy component was considered. The correlation coefficient (r) between BMI and Mesomorphy for males was 0.79 (p <.05) and that for females was 0.81 (p<.05).
The correlation coefficient (r) between BMI and Fat % was only 0.38 for males and that for females was 0.52. Good positive correlations were observed between BMI and FFM for both groups (r=0.61 for males and r=0.56 for females). The poor correlations between BMI and Fat % of the present study indicated that BMI did not necessarily reflect Fat % or fattiness, nor the degree of obesity. However, good positive correlations between BMI and FFM as well as between BMI and Mesomorphy (Muscularity) indicated that BMI values reflected Fat Free Mass (FFM).

Conclusion
Thus from the above study, it can be concluded that, for individuals, BMI is more associated with muscularity than it is with fatness.