Meeting physical activity guidelines is associated with reduced risk for cardiovascular disease in black South African women; a 5.5-year follow-up study.

BACKGROUND: Low levels of physical activity (PA) have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D), but few studies have examined whether meeting international PA guidelines is associated with reduced risk in a black South African (SA) population. The aims of this study were to compare body composition and cardio-metabolic risk factors for CVD and T2D between active and inactive groups (part 1, cross-sectional analysis) and, to determine whether PA level predicts changes in body composition and cardio-metabolic risk factors for CVD and T2D at follow-up after 5.5-years (part 2, longitudinal analysis). METHODS: Part 1 included a sample of 240 apparently healthy black SA women (26 ± 7 years) who underwent the following measurements at baseline: PA (Global Physical Activity Questionnaire (GPAQ)), body composition and regional fat distribution (dual-energy x-ray absorptiometry and computerised tomography), blood pressure, fasting glucose, insulin and lipid concentrations. For part 2, a sub-sample of women (n = 57) underwent the same measurements after a 5.5-year period. RESULTS: At baseline, 61% of women were classified as meeting the guidelines for moderate- to vigorous-intensity physical activity (MVPA) according to GPAQ. Women who were active had significantly lower body weight (p < 0.001), body fat (BMI, fat mass, % body fat, waist circumference, central and appendicular fat mass, all p < 0.001), and measures of insulin resistance (fasting serum insulin and HOMA-IR, both p = 0.01), and higher high-density lipoprotein cholesterol (p = 0.041), compared to the inactive group. At follow-up, all body fat measures increased significantly in both groups and diastolic blood pressure decreased significantly in those who were active at baseline, but did not change in those who were inactive. CONCLUSIONS: Meeting PA guidelines was associated with decreased risk for CVD and T2D in black SA women, but did not prevent the increase in body fat over time. Interventions promoting physical activity to specifically address obesity in this high-risk group are recommended.

Determinants of change in body weight and body fat distribution over 5.5 years in a sample of free-living black South African women.

OBJECTIVE: To identify socio-demographic and lifestyle determinants of weight gain in a sample of premenopasual black South African (SA) women. METHODS: Changes in body composition (dual-energy X-ray absorptiometry, computerised tomography), socio-economic status (SES) and behavioural/lifestyle factors were measured in 64 black SA women at baseline (27 ± 8 years) and after 5.5 years. RESULTS: A lower body mass index (BMI) and nulliparity, together with access to sanitation, were significant determinants of weight gain and change in body fat distribution over 5.5 years. In addition, younger women increased their body weight more than their older counterparts, but this association was not independent of other determinants. CONCLUSION: Further research is required to examine the effect of changing SES, as well as the full impact of childbearing on weight gain over time in younger women with lower BMIs. This information will suggest areas for possible intervention to prevent long-term weight gain in these women.

Cardiorespiratory Fitness and Light-Intensity Physical Activity Are Independently Associated with Reduced Cardiovascular Disease Risk in Urban Black South African Women: A Cross-Sectional Study.

BACKGROUND: Low levels of physical activity, poor cardiorespiratory fitness, and a sedentary lifestyle have been associated with increased risk for cardiovascular disease (CVD) and type 2 diabetes (T2D). Few studies have examined their independent associations in an urban black sub-Saharan African population. OBJECTIVES: To examine the independent associations of physical activity, cardiorespiratory fitness, and sedentary time on body composition and cardiometabolic risk factors for CVD and T2D in black South African women. MATERIALS AND METHODS: A subsample (n = 76; 18-45 years) was recruited, as part of a cross-sectional study. Accelerometry, cardiorespiratory fitness, body composition, insulin sensitivity, serum lipids, and blood pressure were measured. RESULTS: Light- but not moderate- to vigorous intensity physical activity was inversely associated with trunk fat mass (r = -0.25, P = 0.03). Sedentary time was associated with triglyceride (TG) (r = 0.36, P = 0.01) and TG/HDL-C (r = 0.34, P = 0.04), and these relationships were independent of body fat. Cardiorespiratory fitness was inversely associated with body fat % (r = -0.34, P = 0.02), central fat mass (r = -0.31, P = 0.03), visceral adipose tissue (VAT, r = -0.47, P < 0.01), and insulin resistance (HOMA-IR; r = -0.41, P = 0.01). The association between cardiorespiratory fitness and HOMA-IR was independent of body fat and physical activity, but not VAT. Cardiorespiratory fitness was inversely associated with sedentary time (r = -0.31, P = 0.03), but not with any of the physical activity variables (P > 0.05). CONCLUSION: Both physical activity and cardiorespiratory fitness were associated with reduced total and central fat mass, VAT, and reduced cardiometabolic risk for CVD and T2D. Longitudinal studies are required to confirm whether the promotion of increasing light physical activity, while reducing sedentary time and increasing cardiorespiratory fitness, reduces the risk for obesity, CVD and T2D.

Longitudinal Changes in Body Fat and Its Distribution in Relation to Cardiometabolic Risk in Black South African Women.

BACKGROUND: Ethnic differences in body composition and cardiometabolic risk have been reported in cross-sectional studies. This study aimed to investigate changes in body composition over 5.5 years, and its association with cardiometabolic risk in premenopausal black South African (SA) women. METHODS: Changes in body composition and body fat distribution (dual-energy x-ray absorptiometry and computerized tomography), fasting glucose, insulin, and lipid concentrations, were measured in 63 black SA women at baseline (age: 27 ± 8 years), and 5.5 years later. RESULTS: Body weight and fat mass (FM) increased by 6.9 ± 9.9 kg and 4.3 ± 6.9 kg, respectively, over the 5.5 years with a relative (%FM) increase in central and decrease in peripheral FM (all P < 0.05). Fasting glucose and lipid concentrations (except HDL-cholesterol) increased over the follow-up period (all P < 0.05). Both baseline and changes in body fat distribution were associated with cardiometabolic risk. Independent of baseline age, FM and insulin sensitivity, baseline trunk:leg was associated with reduced insulin sensitivity at follow-up (Matsuda index; ß = -0.41, P = 0.002). Increasing trunk:gynoid ratio was associated with higher plasma insulin levels (ß = 0.31, P = 0.023) and reduced insulin sensitivity (Matsuda index; ß = -0.52, P < 0.001) at follow-up. CONCLUSIONS: Weight gain in free-living black SA women over 5.5 years was associated with a centralization of fat mass, which predicted an increase in cardiometabolic risk.

Socio-cultural, environmental and behavioural determinants of obesity in black South African women.

South Africa (SA) is undergoing a rapid epidemiological transition and has the highest prevalence of obesity in sub-Saharan Africa (SSA), with black women being the most affected (obesity prevalence 31.8%). Although genetic factors are important, socio-cultural, environmental and behavioural factors, as well as the influence of socio-economic status, more likely explain the high prevalence of obesity in black SA women. This review examines these determinants in black SA women, and compares them to their white counterparts, black SA men, and where appropriate, to women from SSA. Specifically this review focuses on environmental factors influencing obesity, the influence of urbanisation, as well as the interaction with socio-cultural and socio-economic factors. In addition, the role of maternal and early life factors and cultural aspects relating to body image are discussed. This information can be used to guide public health interventions aimed at reducing obesity in black SA women.