In a recent study published in American journal of clinical nutrition, researchers examined the independent associations of body fat percentage (BF%) and waist-to-height ratio (WHtR) and the danger of future coronary heart disease (CVD), including its essential subtypes (ischemic stroke [IS] and myocardial infarction [MI]). While previous work compared the accuracy of a mix of each indices with body mass index [BMI]currently probably the most commonly used approach to estimating obesity, their independent predictive power stays unknown.

Test: Waist-to-height ratio and body fat percentage as risk aspects for ischemic heart problems: a prospective cohort study from the UK Biobank. Photo credit: Crystal Light / Shutterstock

This study used a cohort sample from the UK Biobank, including 468,333 people followed for 12 years. The study results show that WHtR is linearly related to CVD risk. Notably, this rate far exceeds currently existing measures of central obesity, similar to waist-to-hip ratio [WHR] and waist circumference [WC]) in predicting subsequent risk of ischemic heart problems. Contrary to previous hypotheses, BF% showed poor predictive power, suggesting that the assumed predictive power was as a consequence of correlation with WHtR moderately than an independent association with CVD. These findings suggest that WHtR may replace WHR and WC in population-wide obesity censuses and emphasize visceral adipose tissue as a primary goal in weight management interventions.

Entry

Heart problems (CVD) is the leading reason behind human mortality worldwide, killing roughly 17.9 million people annually. Obesity, commonly defined as body mass index (BMI measured in kg/m2²) > 30, is a well-established predictor of CVD. Worryingly, the incidence of obesity has greater than tripled over the past forty years, and roughly 2.3 billion people currently suffer from it. The variety of premature deaths from obesity has correspondingly doubled in only the last 20 years, making it a public health problem requiring urgent population-wide interventions.

Although the association between BMI and heart problems risk is well established, a growing body of literature has criticized the usage of the previous, particularly in determining etiological aspects related to heart problems risk, since it is a general measure of obesity that doesn’t have in mind differences in distribution or composition of adipose tissue. Body fat percentage (BF%) has been suggested to be superior to BMI as a consequence of its relatively accurate measurement of body composition.

Recently, central measures of obesity (similar to waist-to-hip ratio) have been developed [WHR] and waist circumference [WC]) are increasingly being studied as predictors of heart problems risk as a consequence of the additional advantage of measuring the distribution of body fat. Encouragingly, clinical trials increasingly show that central measures of obesity are more accurate predictors of heart problems risk than their general obesity predecessors. One such indicator is the waist-to-height ratio (WHtR), which is calculated by dividing WC by height. The most recent UK obesity guidelines recommend its use as a measure of obesity in the overall population as a consequence of the massive variety of studies showing its association with subsequent CVD risk.

Unfortunately, these studies almost exclusively compared the mix of WC or WHR with BMI, and only just a few studies assessed the association of BF% or WHtR with ischemic CVD. The few studies which have compared the latter have made these comparisons concordantly, with no evidence of an independent effect of BF% or WHtR. It’s price noting that these studies showed misleading results.

Concerning the study

The present study fills this data gap by examining the independent associations of WHtR and BF% with ischemic heart problems. The study cohort was drawn from the UK Biobank, a large-scale, long-term prospective cohort of over 500,000 people aged 40 to 69 years in Wales, Scotland and England. Inclusion criteria for the study included the absence of cardiovascular events at baseline, complete anthropometric data, and ongoing pregnancy through the study period.

Data collection was performed using a bioelectrical impedance analyzer (BIA) for BF%, a telescopic height gauge for height measurement, and a WC tape measure. WHtR was derived from WC and growth. Moreover, sociodemographic, ethnic and health data were obtained from the UK Biobank repository. Finally, physical activity was measured using the Physical Activity Questionnaire. The follow-up period of the study was 12 years, ranging from 2009 to 2021, and outcomes of interest included incident ischemic heart problems (endpoints) and myocardial infarction or IS (endpoints).

Statistical evaluation included each descriptive statistics and proportional hazards calculations. In the primary case, means and standard deviations (SD) were used for continuous data, and frequency and percentages were used for categorical data. Hazard ratios were calculated using Cox proportional hazards models, adjusting for sex, region, age, ethnicity, and education. All models moreover included levels of alcohol, smoking and physical activity. Finally, Pearson correlation coefficients were calculated to look at potential correlations between BF% and WHtR, which can explain previously reported confounds.

Research results and conclusions

Of over 500,000 UK Biobank participants, 468,333 met the study inclusion criteria and were included on this study. During 12 years of follow-up, 20,151 participants experienced CVD-related ischemic events, 13,604 had myocardial infarctions, and 6,681 patients developed IS. Much like previous studies, the present study found central obesity to be a big predictor of heart problems risk. Of note, this association was independent of overall obesity measures (i.e., BMI and BF%). The study highlighted the identification of WHtR as an independent, linearly associated predictor of ischemic heart problems risk. In contrast, while BF% initially showed a linear association with CVD, adjustment to prior WHtR collaboration effectively eliminated this association.

Contrary to popular belief, BF% is just not a great independent predictor of ischemic heart problems, though it’s a more accurate measure of body fat composition than BMI. However, WHtR outperformed all currently used estimates of body fat composition and distribution. This means that intra-abdominal visceral fat plays a pivotal role in CVD pathology and should be the main target of future CVD prevention interventions. Nonetheless, additional studies are essential to find out the mechanism underlying this interaction.