Index of central obesity – A novel parameter

https://doi.org/10.1016/j.mehy.2006.10.038Get rights and content

Summary

Waist circumference (WC) is globally used as a parameter to quantify central obesity, the key culprit in insulin resistance and related disorders. Hitherto globally in various definitions of metabolic syndrome and risk scores, WC is used to quantify central obesity. For defining central obesity, which is a single entity numerous WC cutoffs have been suggested, separately for males and females and various races. We believe that this difference is amenable to differences in their average heights. To quantify proportion of visceral fat in the total body fat, WC alone is not sufficient. We hereby hypothesize that Index of central obesity (ICO) defined by us, as a ratio of WC and height is a better parameter of central obesity. If ICO is used in place of WC we may do away with various WC cutoffs and may have a single cutoff applicable to all races and both genders. Using average heights of various countries and their respective WC cutoffs suggested by IDF consensus definition for defining metabolic syndrome (MS) we derived their ICO cutoffs mathematically. The ICO cutoffs obtained ranged from 0.51 to 0.58 among males and 0.47 to 0.54 among females. The range has narrowed down compared to wide range of cutoffs for WC i.e. 90–102 cm for males and 80–88 cm for females. To test superiority of ICO over WC even among people of same race and same gender we conducted a pilot study in which, we compared two subjects with same WC and body mass index (BMI), though they differed in their stature. Body fat distribution was compared on DEXA and oral glucose tolerance was tested. Percentage of total body fat contributed by truncal fat was 36.11% in taller subject (Dr. P) and 46.31% in the shorter one (Mr. P). On investigation Dr P had normal glucose tolerance while Mr. P was diagnosed to be diabetic. These differences unexplained by identical WC and BMI could be explained by difference in their ICO (0.557 vs 0.645). ICO has a potential to be a better parameter of central obesity. It may obviate the need for numerous WC cutoffs and may even be applicable to children where existing parameters are not useful.

Introduction

Central adiposity has shown a strong association with type 2 DM [1], IR [2], components of metabolic syndrome (MS) [3], [4] and ischaemic stroke [5]. Waist circumference (WC), has also been shown to strongly correlate with hypertension, type 2 DM [6] and all the criteria for MS [3]. WC has been used as a parameter of central obesity in various risk scores and definitions of MS. Following the concern that NCEP ATP III criteria, applied to the Asians, will underestimate the population at risk [7], modifications in WC cutoffs as 90 cm in men and 80 cm in women were suggested [8]. Recently International Diabetes Federation (IDF) has defined metabolic syndrome in which race specific cutoffs for WC are suggested separately for males and females [9]. Though this need for lower limits of WC in Asians is attributed to ethnic differences, it was observed that even within the same population, people with identical WC but different heights have dissimilar risk for hyperglycemia, hypertension and fatty liver [10]. Moreover risk of MI was found to be greater in short than tall men [11] and women [12]. The ethnic difference that has led us to lower cutoffs may be essentially attributed to differences in average height. For a given WC a short person will obviously look more centrally obese than a taller person. Though WC can roughly quantify amount of truncal fat, it cannot effectively gauge its contribution to whole body fat. For the same reason WC is not applicable to quantify central obesity in children.

Section snippets

Hypothesis

Therefore we propose that, to quantify central adiposity (central distribution of fat), height, as a parameter must be taken into consideration. Here we hypothesize that index of central obesity (ICO) defined by us, as a ratio of WC and height correlates better with central obesity than WC alone. It is important to include height as a denominator, as other areas in body have effects opposite to that of fat in central region. WC alone can quantify fat in central region, but would miss the

Evaluation of hypothesis

Using average heights of various countries and WC cutoffs suggested by IDF for the country, ICO was obtained separately for males and females (Table 2). The ICO cutoffs obtained ranged from 0.51 to 0.58 among males and 0.47 to 0.54 among females. This novel parameter narrowed down the wide range of WC cutoffs suggested by IDF, which vary from 90 cm to 102 cm for males and 80 cm to 88 cm for females. The small difference in cutoffs obtained for males and females may even allow us to have a common

Pilot study

In a pilot study we compared body fat distribution in two persons of identical WC and BMI but of different heights. We present its correlation with ICO, in this pilot study to test the putative concept.

Study design and methods

Two subjects, Dr. P (First Author) and Mr. X, were selected. Both have identical WC and BMI, but different heights. Clinically all major medical disorders were ruled out. Neither was on any drug that would potentially alter body fat composition. Complete physical examination was performed and auxological parameters like height, weight, BMI and WC were measured. WC was measured in full expiration at the level of the narrowest part between lower border of rib cage and iliac crest. Photographs of

Results

On visual impression the subjects clearly appeared to differ in their body fat distribution. Dr. P looked generally obese and Mr. X was obviously centrally obese (Photograph 1). WC (98 cm) and BMI (28.8) were identical for the two. Total body fat of Dr. P was 26.2 kg while that of Mr. X 15.8 kg (Table 1). Their truncal fat was 9.5 kg and 7.4 kg, respectively, though percentage of total body fat contributed by truncal fat was 36.11% and 46.31%, respectively. On investigation Dr P had normal glucose

Discussion

Off late significant emphasis has been laid on central adiposity and many studies have shown a strong correlation of WC with all derangements related to IR. WC is the only auxological parameter, included in NCEP diagnostic criteria for MS. In view of suggestions that gluteofemoral fat [13], leg fat [14] and muscle mass are protective against IR, contribution of central fat in the total body composition becomes all the more important. For quantifying it, height must be considered in addition to

Conclusions

ICO can supplant WC as a better parameter of central adiposity and perhaps even eliminate the confusion emanating from lack of consensus on race-appropriate cutoffs. Even at individual level, ICO probably can quantify central obesity more accurately, height being considered as a variable. It may even do well if used in different risk scores like diabetes risk score, in place of WC. It may be effective for quantifying childhood central adiposity as well.

References (15)

There are more references available in the full text version of this article.

Cited by (70)

  • Population density and obesity in rural China: Mediation effects of car ownership

    2022, Transportation Research Part D: Transport and Environment
  • Resected gastric volume has no influence on early weight loss after laparoscopic sleeve gastrectomy

    2018, Surgery for Obesity and Related Diseases
    Citation Excerpt :

    The present study did not demonstrate a significant correlation between the RGV and sex, but the P value was close to the significance level (P = .057), suggesting that a sex difference might really exist. If a sex difference does indeed exist, it could be due to the fact that men have a greater predilection for central obesity [27]. The main finding of the present study was that the %EWL-1 yr after LSG is correlated with RGV/weight and RGV/BMI, and not with RGV.

  • Metabolic syndrome in retired soccer players: A pilot study

    2017, Obesity Medicine
    Citation Excerpt :

    Another parameter, the index of central obesity (ICO) (Parikh et al., 2007), reflecting the ratio of WC to the height, was also determined, as a reliable tool for MetS (Parikh et al., 2009). ICO cut-offs ranging between 0.51–0.58 were indicative of a healthy BW accumulation (Parikh et al., 2007), whereas ICO greater than 0.58 was determined in participants with increased visceral adiposity. Birth weight was also recorded for all subjects and as far as the RSP group was concerned, body weight before retirement from their athletic career was additionally reported.

View all citing articles on Scopus
View full text