CARDIOVASCULAR JOURNAL OF AFRICA • Vol 23, No 9, October 2012
AFRICA
517
within the African continent. The majority of African countries
are undergoing swift changes in their social and economic
environments, concommitant with changes in food-consumption
patterns.
51
The increasing availability of food and its diversity in
urban areas has been shown to particularly influence the quality
of diets and nutritional well-being.
52
These changes in diet and
lifestyle, especially in urban settings, often involve a shift from
the consumption of traditional staple foods low in fat and rich in
fibre, to processed and refined foods, meat and dairy products,
high in saturated fats and sugar.
52-54
The consequence of urbanisation, which is often connected
with the adoption of a lifestyle commonly referred to as
‘
westernisation’, is the increased intake of energy-dense foods
and high-calorie sugary meals and drinks.
55-57
Urbanisation is
also associated with less energy-demanding jobs, complemented
by increased sedentary lifestyles and the adoption of detrimental
eating habits, which include the regular consumption of fast food
and so called ‘eat out’.
55-57
With increasing economic development and urbanisation
comes the proliferation of fast-food chains, and easy and
cheaper means of transport, which are mostly patronised by the
affluent. All of these factors above may have contributed to the
higher prevalence of obesity noticed in the urban and affluent
populations ofAfrican countries. Changes in lifestyle are therefore
convincingly implicated as causative factors in the observed
higher prevalence of obesity in urban than in rural populations.
Existing studies have also implicated urbanisation in
the increasing burden of co-morbidities of obesity such as
cardiovascular disease (CVD), type 2 diabetes and hypertension.
For instance, the study by Niakara and co-workers in a West
African urban environment revealed a high incidence of
hypertension (40.2% in a sample of 2 087 participants).
58
A
similar study by Sobngwi
et al
.
59
also associated urbanisation
and socio-economic factors as driving forces in the increasing
prevalence of hypertension in West Africa.
59
Similarly, Amoah
33
and Jackson
et al.
30
reported a positive
association of age with overweight and obesity. They identified
middle-aged respondents as having the highest prevalence of
obesity, which began to decline from the age of 65 years. This
links increasing age with the development of obesity, a factor
that should be considered by policy makers when addressing
obesity in the African continent. The decline in prevalence of
obesity in older age has also been noticed in other parts of the
world.
60,61
The results of this review also suggest a higher prevalence
of obesity in the female population compared to their male
counterparts. This higher prevalence in women depicts the global
situation in most populations of African origin, including those
in the diaspora.
34,62,63
Although there is no direct comparison,
about 77% of African women in the diaspora are reportedly
overweight or obese, typifying the female gender as the most
obese population compared with their male counterparts as well
as with males of all other ethnic groups.
43,61
Preferred body image may be a key factor in obesity
among African women.
64
Numerous studies suggest a preference
for overweight over normal BMI among African women.
65,66
Moreover, cultural perceptions concerning obesity and
overweight may also have played a role in the high prevalence
of overweight and obesity among women, and central obesity
among affluent men in this review.
Culture is known to shape health behaviour and serves as
a mirror for perceiving and interpreting experiences.
67,68
In
several parts of Africa, obesity is currently held with little
opprobrium,
69,70
people generally associating fatness with beauty,
fame and evidence of good living and health,
33,65,71
particularly in
women.
72
In some cases, women are fattened up for suitors prior
to marriage,
73,74
as a sign of beauty and fertility. Furthermore,
African men are purported to have a preference for overweight
over thin women.
33
Although affluence, effects of urbanisation and excess
consumption of food are mainly implicated in the increased
prevalence of obesity on the African continent (as suggested by
this review), food insecurity may also be a factor to consider
at the other end of socio-economic spectrum.
64
Townsend and
colleagues
75
suggested a positive association of food insecurity
with overweight in women, while Chaput
et al
.
76
linked food
insecurity to overweight status in women but not in men in
Uganda. Conclusively, women of all socio-economic strata in
the African continent can be said to be at risk of developing
overweight and obesity, albeit through diverse mechanisms,
which may necessitate further research.
From all three studies comparing cardiovascular and
inflammatory bio-markers, results showed that the levels of
leptin, hsCRP and fibrinogen were significantly higher in African
women. African women also had higher blood pressures and
vascular resistance than their Caucasian counterparts. However
this condition may have been induced by different factors, such
as sodium sensitivity, which is an important condition in the
African population.
77
It is also notable that, although black South
Africans had higher blood pressures, vascular resistance, and
fibrinogen and leptin levels than their Caucasian counterparts,
the relationships of these markers with obesity were markedly
weaker than those of Caucasians, suggesting that the mechanisms
to elucidate the weaker correlations of cardiovascular indices and
obesity in the African population remain unresolved.
32
The above results also imply that the level of clinical markers
should not necessarily be compared between ethnic groups,
as the effectiveness and sensitivity of a specific biochemical
marker might be completely different in an ethnically distinct
group. Findings further raise the question whether obesity
should be regarded as a cardiovascular threat to these women. By
contrast, given that the obesity measures of African women were
strongly linked with markers that are more associated with type
2
diabetes, such as triacylglycerols, inflammation and insulin
resistance, this suggests that obesity in African women may have
a primary effect on the development of diabetes, and secondarily
on cardiovascular disease.
Earlier studies in South Africa have shown ischaemic heart
disease (IHD) to be more prevalent among Europeans,
21,78-80
while type 2 diabetes
81-83
and hypertension
84
were more common
among Africans. Although the metabolic reasons behind these
differences remain complex, more recent studies suggest that
black South Africans have a less atherogenic fasting lipid profile
than their white counterparts.
85-87
Crowther
et al
.
87
also observed
greater amounts of visceral fat and waist-to-hip ratios in obese
whites than in obese black individuals.
87
Given that the study by Schutte
et al
.
32
did not include
environmental influences in its investigationof these relationships,
caution should be applied in the interpretation of these results.
The seasonal variation in the collection of data and assay dates
