Body shape index

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A Body Shape Index (ABSI) [1] or simply body shape index (BSI) is a metric for assessing the health implications of a given human body height, mass and waist circumference (WC). The inclusion of WC is believed to make the BSI a better indicator of risk of mortality from excess weight than the standard body mass index. [2] [3] ABSI correlates only slightly with height, weight and BMI, indicating that it is independent of other anthropometric variables in predicting mortality.

A criticism of BMI is that it does not distinguish between muscle and fat mass and so may be elevated in people with increased BMI due to muscle development rather than fat accumulation from overeating. [4] A higher muscle mass may actually reduce the risk of premature death. [5] A high ABSI appears to correspond to a higher proportion of central obesity, or abdominal fat.

In a sample of Americans in the National Health and Nutrition Examination Survey, death rates in some subjects were high for both high and low BMI and WC, a familiar conundrum associated with BMI. [6] In contrast, death rates increased  proportionally with increased values of ABSI. The linear relationship was unaffected by adjustments for other risk factors including smoking, diabetes, elevated blood pressure and serum cholesterol.

The equation for ABSI is based on statistical analysis and is derived from an allometric regression. With waist and height in meters and weight in kg), [7] .

Studies have associated ABSI with total mortality and cardiovascular risk, indicating that it is useful in assessing cardio-metabolic risks. [8]

ABSI over age diagram female ABSI-vs-Age-Female.png
ABSI over age diagram female
ABSI over age diagram male ABSI-vs-Age-Male.png
ABSI over age diagram male

If the ABSI is above 0.083, an increased risk is assumed; a value of 0.091 is said to represent a doubling of the relative risk. The ABSI is classified into risk classes by means of the ABSI-z value (z-Value) derived from the ABSI. The ABSI-z is calculated from the deviation of the ABSI from the ABSI mean in relation to the standard deviation. The ABSI means and standard deviations are age- and sex-dependent empirically determined and tabulated. [7] The calculation is made according to the following formula

with the indices mean: average and std: standard deviation. [7]

The ABSI-z allows classification into the following risk groups for health risk.

ABSI-z risk groups
ABSI-z valueRisk
Less than -0.868Very low
Between -0.868 and -0.272Low
Between -0.272 and +0.229Average
Between +0.229 and +0.798High
Greater than +0.798Very high

To understand the ABSI, it is important to know the relationship between waist circumference and weight. A reduction in weight alone does not necessarily lead to a better risk class. The ABSI uses the waist circumference to take into account the distribution of fat, especially the proportion of abdominal fat. In other words, a reduction in weight and a constant waist circumference worsens the risk classification, while an increase in weight with the same waist circumference leads to an improvement. Thus, more muscle with a small waist circumference leads to a better risk classification. This is a significant difference to BMI. The following diagram shows the progression of risk groups as a function of weight and waist circumference using the example of a 35-year-old man.

ABSIz risk groups in waist circumference over weight. The diagram shows the progression of risk groups as a function of weight and waist circumference using the example of a 35-year-old man. ABSIz-WC-weight-diagram.png
ABSIz risk groups in waist circumference over weight. The diagram shows the progression of risk groups as a function of weight and waist circumference using the example of a 35-year-old man.

Related Research Articles

<span class="mw-page-title-main">Body mass index</span> Relative weight based on mass and height

Body mass index (BMI) is a value derived from the mass (weight) and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is expressed in units of kg/m2, resulting from mass in kilograms (kg) and height in metres (m).

<span class="mw-page-title-main">Abdominal obesity</span> Excess fat around the stomach and abdomen

Abdominal obesity, also known as central obesity and truncal obesity, is the human condition of an excessive concentration of visceral fat around the stomach and abdomen to such an extent that it is likely to harm its bearer's health. Abdominal obesity has been strongly linked to cardiovascular disease, Alzheimer's disease, and other metabolic and vascular diseases.

<span class="mw-page-title-main">Obesity</span> Medical condition in which excess body fat harms health

Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it can potentially have negative effects on health. People are classified as obese when their body mass index (BMI)—a person's weight divided by the square of the person's height—is over 30 kg/m2; the range 25–30 kg/m2 is defined as overweight. Some East Asian countries use lower values to calculate obesity. Obesity is a major cause of disability and is correlated with various diseases and conditions, particularly cardiovascular diseases, type 2 diabetes, obstructive sleep apnea, certain types of cancer, and osteoarthritis.

Human body weight is a person's mass or weight.

<span class="mw-page-title-main">Waist</span> Part of the abdomen between the rib cage and hips

The waist is the part of the abdomen between the rib cage and hips. Normally, the waist is the narrowest part of the torso.

<span class="mw-page-title-main">Underweight</span> Below a weight considered healthy

An underweight person is a person whose body weight is considered too low to be healthy. A person who is underweight is malnourished.

<span class="mw-page-title-main">Waist–hip ratio</span>

The waist–hip ratio or waist-to-hip ratio (WHR) is the dimensionless ratio of the circumference of the waist to that of the hips. This is calculated as waist measurement divided by hip measurement. For example, a person with a 75 cm waist and 95 cm hips has WHR of about 0.79.

The body fat percentage of an organism is the total mass of its fat divided by its total body mass, multiplied by 100; body fat includes essential body fat and storage body fat. Essential body fat is necessary to maintain life and reproductive functions. The percentage of essential body fat for women is greater than that for men, due to the demands of childbearing and other hormonal functions. Storage body fat consists of fat accumulation in adipose tissue, part of which protects internal organs in the chest and abdomen. A number of methods are available for determining body fat percentage, such as measurement with calipers or through the use of bioelectrical impedance analysis.

<span class="mw-page-title-main">Body shape</span> General shape of a human body

Human body shape is a complex phenomenon with sophisticated detail and function. The general shape or figure of a person is defined mainly by the molding of skeletal structures, as well as the distribution of muscles and fat. Skeletal structure grows and changes only up to the point at which a human reaches adulthood and remains essentially the same for the rest of their life. Growth is usually completed between the ages of 13 and 18, at which time the epiphyseal plates of long bones close, allowing no further growth.

The obesity paradox is the finding in some studies of a lower mortality rate for overweight or obese people within certain subpopulations. The paradox has been observed in people with cardiovascular disease and cancer. Explanations for the paradox range from excess weight being protective to the statistical association being caused by methodological flaws such as confounding, detection bias, reverse causality, or selection bias.

<span class="mw-page-title-main">Overweight</span> Above a weight considered healthy

Being overweight is having more body fat than is optimally healthy. Being overweight is especially common where food supplies are plentiful and lifestyles are sedentary.

<span class="mw-page-title-main">Female body shape</span> Cumulative product of the human female skeletal structure and distribution of muscle and fat

Female body shape or female figure is the cumulative product of a woman's bone structure along with the distribution of muscle and fat on the body.

<span class="mw-page-title-main">Classification of obesity</span> Overview of the classification of the condition of obesity

Obesity classification is a ranking of obesity, the medical condition in which excess body fat has accumulated to the extent that it has an adverse effect on health. The World Health Organization (WHO) classifies obesity by body mass index (BMI). BMI is further evaluated in terms of fat distribution via the waist–hip ratio and total cardiovascular risk factors. In children, a healthy weight varies with sex and age, and obesity determination is in relation to a historical normal group.

<span class="mw-page-title-main">Android fat distribution</span> Distribution of human adipose tissue mainly around the trunk and upper body

Android fat distribution describes the distribution of human adipose tissue mainly around the trunk and upper body, in areas such as the abdomen, chest, shoulder and nape of the neck. This pattern may lead to an "apple”-shaped body or central obesity, and is more common in males than in females. Thus, the android fat distribution of men is about 48.6%, which is 10.3% higher than that of premenopausal women. In other cases, an ovoid shape forms, which does not differentiate between men and women. Generally, during early adulthood, females tend to have a more peripheral fat distribution such that their fat is evenly distributed over their body. However, it has been found that as females age, bear children and approach menopause, this distribution shifts towards the android pattern of fat distribution, resulting in a 42.1% increase in android body fat distribution in postmenopausal women. This could potentially provide evolutionary advantages such as lowering a woman's center of gravity making her more stable when carrying offspring.

The body adiposity index (BAI) is a method of estimating the amount of body fat in humans. The BAI is calculated without using body weight, unlike the body mass index (BMI). Instead, it uses the size of the hips compared to the person's height.

A person's waist-to-height ratio (WHtR), occasionally written WtHR or called waist-to-stature ratio (WSR), is defined as their waist circumference divided by their height, both measured in the same units. It is used as a predictor of obesity-related cardiovascular disease. The WHtR is a measure of the distribution of body fat. Higher values of WHtR indicate higher risk of obesity-related cardiovascular diseases; it is correlated with abdominal obesity.

<span class="mw-page-title-main">TOFI</span> Individual with disproportionate amount of fat

TOFI (thin-outside-fat-inside) is used to describe lean individuals with a disproportionate amount of fat stored in their abdomen. The figure to illustrate this shows two men, both 35 years old, with a BMI of 25 kg/m2. Despite their similar size, the TOFI had 5.86 litres of internal fat, whilst the healthy control had only 1.65 litres.

Normal weight obesity is the condition of having normal body weight, but with a high body fat percentage, leading to some of the same health risks as obesity.

The association between obesity, as defined by a body mass index of 30 or higher, and risk of a variety of types of cancer has received a considerable amount of attention in recent years. Obesity has been associated with an increased risk of esophageal cancer, pancreatic cancer, colorectal cancer, breast cancer, endometrial cancer, kidney cancer, thyroid cancer, liver cancer and gallbladder cancer. Obesity may also lead to increased cancer-related mortality. Obesity has also been described as the fat tissue disease version of cancer, where common features between the two diseases were suggested for the first time.

Relative Fat Mass (RFM) is a simple formula for the estimation of overweight or obesity in humans that requires only a calculation based on a ratio of height and waist measurements.

References

  1. ↑ Christakoudi, Sofia; Tsilidis, Konstantinos K.; Muller, David C.; Freisling, Heinz; Weiderpass, Elisabete; Overvad, Kim; Söderberg, Stefan; Häggström, Christel; Pischon, Tobias; Dahm, Christina C.; Zhang, Jie (2020-09-03). "A Body Shape Index (ABSI) achieves better mortality risk stratification than alternative indices of abdominal obesity: results from a large European cohort". Scientific Reports. 10 (1): 14541. Bibcode:2020NatSR..1014541C. doi: 10.1038/s41598-020-71302-5 . ISSN   2045-2322. PMC   7471961 . PMID   32883969.
  2. ↑ "Doctors expose BMI shortcomings". London Evening Standard. Evening Standard Limited. 2006-01-18. Retrieved 2013-09-12.
  3. ↑ "New study supports body shape index as predictor of mortality". EurekAlert!. Retrieved 2019-06-25.
  4. ↑ Nevill, Alan M.; Stewart, Arthur D.; Olds, Tim; Holder, Roger (2006). "Relationship between adiposity and body size reveals limitations of BMI". American Journal of Physical Anthropology. 129 (1): 151–156. doi:10.1002/ajpa.20262. hdl: 2436/8003 . ISSN   0002-9483. PMID   16270304.
  5. ↑ Bigaard, Janne; Frederiksen, Kirsten; Tjønneland, Anne; Thomsen, Birthe Lykke; Overvad, Kim; Heitmann, Berit Lillienthal; Sørensen, Thorkild I.A. (July 2004). "Body Fat and Fat-Free Mass and All-Cause Mortality". Obesity Research. 12 (7): 1042–1049. doi: 10.1038/oby.2004.131 . PMID   15292467.
  6. ↑ Ahima, R. S.; Lazar, M. A. (2013-08-23). "The Health Risk of Obesity--Better Metrics Imperative". Science. 341 (6148): 856–858. Bibcode:2013Sci...341..856A. doi:10.1126/science.1241244. ISSN   0036-8075. PMID   23970691. S2CID   9179758.
  7. 1 2 3 Krakauer, Nir Y.; Krakauer, Jesse C. (2012-07-18). Li, Shengxu (ed.). "A New Body Shape Index Predicts Mortality Hazard Independently of Body Mass Index". PLOS ONE. 7 (7): e39504. Bibcode:2012PLoSO...739504K. doi: 10.1371/journal.pone.0039504 . ISSN   1932-6203. PMC   3399847 . PMID   22815707.
  8. ↑ Bertoli, Simona; Leone, Alessandro; Krakauer, Nir Y.; Bedogni, Giorgio; Vanzulli, Angelo; Redaelli, Valentino Ippocrates; De Amicis, Ramona; Vignati, Laila; Krakauer, Jesse C. (2017-09-25). Wang, Guoying (ed.). "Association of Body Shape Index (ABSI) with cardio-metabolic risk factors: A cross-sectional study of 6081 Caucasian adults". PLOS ONE. 12 (9): e0185013. Bibcode:2017PLoSO..1285013B. doi: 10.1371/journal.pone.0185013 . ISSN   1932-6203. PMC   5612697 . PMID   28945809.
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