Cardiovascular Journal of Africa: Vol 30 No 6 (November/December 2019)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 30, No 6, November/December 2019

328

AFRICA

between measures of body fat distribution (VAT, android,

gynoid and leg %FM) and triglyceride concentrations were more

pronounced in women than men. This finding is supported by the

results of the Framingham Heart study,

where the relationship

between VAT in particular and triglyceride concentrations was

stronger in women than men, likely explained by the higher rates

of lipolysis of VAT in women compared to men.

Greater lower-body peripheral fat mass was associated with

a lower cardiometabolic risk, commensurate with findings from

previous studies in African American and Caucasian men and

women.

Similarly, the protective effect of lower-body peripheral

fat was observed in a large sample of Asian men and women,

showing that those with the MetS had less lower-body peripheral

fat that those without the MetS.

Notably, the study by Shorr

et al.

which examined

the differences between gender, body composition and

cardiometabolic risk, showed the protective effect of lower-body

fat to be stronger in women than men, which supports our study

results. The lower-body fat depot is seen as a ‘metabolic sink’,

which traps excess free fatty acids due to the increased lipoprotein

lipase activity and lower lipolytic activity in this depot compared

to the abdominal fat depot, thus protecting other tissues from

lipid overflow and insulin resistance associated with ectopic

lipotoxicity.

11,12,44

The protective effect of lower-body peripheral

fat on triglyceride concentrations was however not observed

in the sample of men, who had significantly less lower-body

peripheral fat than women.

We found positive associations between arm fat and

cardiometabolic risk, in particular insulin resistance, similar

to those found with central adiposity. A possible explanation

for this may be that upper-body adiposity is more sensitive

to lipolysis and secretes a greater number of inflammatory

cytokines.

Accordingly, not all peripheral fat may be regarded

as protective and these differences should be further investigated.

Contrary to the findings for triglyceride and HDL-C

concentrations, TC and LDL-C concentrations were not

associated with body fat in either men or women. This is at

variance with findings from similar studies in other ethnic

groups,

but similar to those shown in black SA women.

These findings suggest that factors other than body fat and its

distribution, including genetics, dietary intake, physical activity

and smoking influence HDL-C, TC and LDL-C concentrations.

Commensurate with the decline in oestrogen following

menopause, the post-menopausal women had greater VAT

and lower gynoid %FM compared to pre-menopausal women,

corresponding to their greater cardiometabolic risk, as previously

demonstrated.

18,19

However, the association between body fat

distribution and cardiometabolic risk was weaker in the post-

compared to pre-menopausal women. A possible explanation for

this is that as oestrogen levels decline and levels of bioavailable

testosterone increase at menopause, this results in a shift in body

weight and body fat distribution and disruptions in glucose

regulation.

Interestingly, studies have shown that aging and lack

of physical activity rather than menopause are the main reasons

for weight gain and obesity in midlife women.

This study adds to the literature the associations between

body composition and cardiometabolic risk factors in the mixed-

ancestry population, which previously had not been researched.

In particular, the women in our study had higher VAT than the

men, which is in contrast to other studies and ethnicities.

This is

possibly due to the vast difference in total body fat between men

and women, which may be unique in this sample. Additionally,

post-menopausal women had increased VAT compared to

pre-menopausal women, which is commensurate with recent

literature.

In clinical practice the importance of preventing

weight gain and centralisation of body fat prior to menopause

should be highlighted. Even though the women in our study had

substantially more abdominal SAT, the relationship between

abdominal SAT and insulin resistance was stronger in the men,

a finding similar to that of the Netherlands Epidemiology of

Obesity study.

The strengths of the study include the proven accuracy

of DXA to measure body composition, and the use of

robust analytical approaches to carefully explore the targeted

associations. Although there were multiple comparisons, the

relationships were consistent, which suggests that false-positive

results were unlikely.

Possible limitations were the cross-sectional nature of the

study and the inclusion of a convenient sample of women and

only a small sample of men. However, this is typical of a South

African population survey in which more women are usually

included than men.

Furthermore, the gender disparities in

obesity prevalence shown in this study are similar to those

reported in the national prevalence data.

We did not have an objective measure of menopausal age.

These findings could therefore reflect an age effect and warrant

further investigation. We lacked information on important

potential confounders such as socio-economic status, diet,

physical activity and smoking, which are known to affect body

fat and cardiometabolic risk. In addition, we did not adjust for

medication use, but the participants were instructed not to take

any medications prior to testing.

Conclusion

Central fat mass was associated with increased cardiometabolic

risk, and lower body peripheral fat mass was associated with

reduced risk. However, these associations were influenced

by gender and menopausal status. Notably, VAT was the

most consistent and significant correlate of insulin resistance.

Future studies should focus on the mechanisms underlying

the gender-specific associations between SAT (in particular

dSAT and sSAT) and cardiometabolic risk. Additionally, the

relationship between DXA-derived VAT and SAT and simpler

anthropometry measurements to predict cardiometabolic

risk should be investigated. Specific VAT cut-off points for

cardiometabolic risk in the mixed-ancestry populations should

be derived in an effort to identify high-risk individuals.

We thank the Bellville South (Ward 009) community for participating in the

study. We are also grateful to the Bellville South Community Health Forum

for supporting the engagement with the Bellville South community.

This research project was funded by the South African Medical Research

Council (SAMRC) with funds from National Treasury under its Economic

Competitiveness and Support Package (MRC-RFA-UFSP-01-2013/ VMH

Study) and strategic funds from the SAMRC received from the South African

National Department of Health. Any opinion, finding and conclusion or

recommendation expressed in this material is that of the author(s) and the

SAMRC does not accept any liability in this regard. FED was funded by the

Cape Peninsula University of Technology research fund (URF).