| Summary: | Introduction:
High rates of obesity occur in black South African women, up to double the rate
in whites. Concern about the potential health burden of obesity in these women
as well as a lack of understanding of the underlying mechanisms of obesity,
motivated the POWIRS study (Profiles of Women with the Insulin Resistance
Syndrome).
Subjects and methods:
The study population consisted of 100 urbanised black women of the North-
West Province, South Africa. These women were recruited as apparently
healthy, non-pregnant selected volunteers, with ages of 19 to 50 years. Using a
cross-sectional comparative study design, the women were divided into a
normal-weight, overweight and obese group. Relevant demographic,
anthropometric, dietary intake, and serum and plasma variables associated with
the metabolic syndrome were compared in these three groups. Descriptive
statistics, partial Spearman correlations, odds ratios and effect sizes were
calculated. A medium effect size (d ≥ 0.5) indicated possible practical
significance, while a large effect size (d ≥ 0.8) indicated practical significance.
Results:
The acute-phase proteins serum (s)-C-reactive protein, plasma (p)-fibrinogen
and possibly p-plasminogen activator inhibitor-I (PAI-1) had practical significantly
higher levels in the obese than the normal-weight women. High-risk levels of s-
C-reactive protein (≥ 3 mglL) occurred in 68% of the obese women compared to
16% of the normal-weight women. Increased p-PAI-1 levels (> 7 U/ml) occurred
in 46% of the obese compared to 24% of the normal-weight women. Of the
metabolic syndrome components, s-C-reactive protein showed the strongest
correlation with body mass index (r = 0.60, p < 0.0001). Metabolic syndrome
components s-uric acid, s-fasting glucose, s-2h-post-load glucose, s-fasting
insulin and the HOMA-insulin-resistance index had practical significantly higher
levels in the obese than the normal-weight women, while systolic and diastolic
blood pressure, s-gamma-glutamyl-transferase (GGT) and s-triglycerides had
higher levels indicative of practical significance (d ≥ 0.5). The metabolic
syndrome was diagnosed in 38% of the obese women, 8% of the overweight
women and in none of the normal-weight women. The acute-phase protein s-C-reactive
protein, but not p-fibrinogen and p-PAI-1, had higher levels indicative of
practical significance in women with compared to those without the metabolic
syndrome. Serum-C-reactive protein and p-PAI-1 were positively associated with
the HOMA-insulin-resistance index (r = 0.25, p < 0.05 and r = 0.22, p < 0.05,
respectively).
After exclusion of dietary under-reporters, the obese women compared to the
normal-weight women had practical significantly higher daily intakes of the
following: total energy (10 591 versus 8 419 kJ), total carbohydrates (311 g
versus 257 g), total protein (97 g versus 69 g), animal protein (62 g versus 40 g),
total fat (86 g versus 66 g), saturated fat (28 g versus 21 g) and dietary fibre (22
g versus 17 g). A high frequency of overeating incidents (38 - 59%) and
emotion-induced eating (48%) occurred in women of all body-weight groups,
probably representing barriers to successful weight control. Therefore, emotion-induced
eating may be a possible risk factor for the development of obesity and a
factor in the maintenance thereof in this population group.
Attitudes towards weight control and thinness did not differ practical significantly
between the three groups of women. However, with increasing body mass index
more women had a positive attitude towards thin people. None of the women
had a negative attitude towards thin people and weight control. Obese women
had better knowledge (d ≥ 0.5) of the relationship between obesity, nutrition and
health than the normal-weight women.
The majority of the obese women (87%), 81% of the overweight and 12% of the
normal-weight women indicated that they should lose weight. Forty-five percent
of the obese women, 44% of the overweight women and 16% of the normalv
weight women had been on weight reducing diets before. At the time of the
study, 71% of the obese, 60% of the overweight and 11% of the normal-weight
women indicated that they were currently trying to lose weight.
Conclusions:
In a group of 100 urbanised black women of the North-West Province, South
Africa, levels of the acute-phase proteins C-reactive protein, fibrinogen and
possibly PAI-1, were practical significantly higher in obese than normal-weight
women. C-reactive protein, but not fibrinogen and PAI-1 may be part of the
metabolic syndrome in these women. Since prospective studies have shown that
C-reactive protein, PAI-1 and fibrinogen are predictors of myocardial infarction,
stroke and non-insulin-dependent diabetes mellitus (NIDDM), this study indicates
that obesity may lead to an increased health risk in this population.
The women in this study had a more Westernised attitude towards body size and
weight control, which could improve compliance with weight control programmes.
However, the barriers to successful weight control in these women should be
addressed, for example emotion-induced eating. Since the obese women had
better knowledge of the relationship between obesity, nutrition and health than
the normal-weight women, lack of knowledge may not represent a barrier to
successful weight control in these women.
Recommendations:
It is recommended that the dietary analysis should be repeated in a larger
sample of women. These results should motivate urgent development of
culturally-sensitive weight control programmes for obese African women. Such
programmes could prevent an enormous burden due to obesity and its health
consequences on public health resources of this country in the decades to come.
Further research of the underlying mechanisms leading to obesity in this
population group is strongly recommended, especially the role of emotion-induced
eating. === Thesis (Ph.D. (Dietetics))--North-West University, Potchefstroom Campus, 2005.
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