[Truncated abstract] Obesity is now a major public health problem worldwide. More than half the Australian population is now overweight. This is an important public health concern primarily because of the impact of overweight and obesity on risk of diabetes, hypertension and cardiovascular disease. Many strategies have been proposed to fight the obesity epidemic. One possible strategy involves understanding of the role of dietary components in the control of food intake. In this regard, dietary protein and fibre appear to be the most satiating nutrients. Foods enriched in protein, replacing energy from carbohydrate, or dietary fibre can increase satiety and reduce energy intake in the short-term. Longer-term trials suggest benefits of increasing protein or fibre intake on weight loss and features of the metabolic syndrome. The effects of dietary approaches which increase both protein and fibre at the expense of refined carbohydrate are uncertain. A practical approach to increasing both protein and fibre content of processed foods is to incorporate high protein and fibre ingredients into high carbohydrate foods. Lupin kernel flour is a novel food ingredient derived from the endosperm of lupin. It contains 40 to 45% protein, 25 to 30% fibre, and negligible sugar and starch. Lupin kernel flour can be incorporated into refined carbohydrate rich foods such as bread to increase protein and fibre content at the expense of refined carbohydrate. ... Body weight was measured every 2 weeks throughout the 16 week intervention, and these data were analysed to determine whether there was any between group difference in the rate of change in weight over 16 weeks. Over 16 weeks, lupin bread compared to white bread resulted in a significant increase in protein (13.7 (2.3, 25.0) g/d) and fibre (12.5 (8.8, 16.2) g/d) intakes, and a decrease in carbohydrate intake (-19.9 (-45.2, 5.5) g/d). There was a significant difference between groups in the rate of weight change over the 16 weeks (P=0.05). However, at 16 weeks there was no significant effect on body weight (-0.4 (-1.3, 0.6) kg), fat mass (-0.5 (-1.2, 0.2) kg) or fat free mass (0.2 (-0.5, 0.8) kg). Plasma adiponectin and leptin were not altered. Mean 24 hour systolic blood pressure (-2.4 (-3.4, -1.3) mm Hg) and pulse pressure (-3.1 (-3.9, -2.3) mm Hg) were lower for lupin relative to white bread, but diastolic blood pressure was not significantly different between groups. Apart from a lower HDL cholesterol for lupin relative to white bread (-0.09 (-0.17, -0.01) mmol/L), there were no significant differences in other blood lipids and glucose and insulin concentrations. Interpretation of the results was not influenced after adjustment for potential confounding factors. These studies assessed effects of bread enriched in lupin kernel flour relative to white bread, resulting in a higher protein and fibre intake and lower refined carbohydrate intake. This increased satiety and reduced energy intake acutely, but did not significantly influence body weight over 16 weeks. Systolic blood pressure and pulse pressure were significantly reduced. There were no significant improvements in blood lipids or glucose and insulin concentrations. Therefore, increasing protein and fibre intake at the expense of refined carbohydrate using lupin kernel flour may benefit satiety and blood pressure. Longer-term trials incorporating weight loss may be needed to observe benefits on body weight.

The objective of this thesis was to determine the association of leg length (LL), a marker of early childhood conditions, with metabolic abnormalities underlying type 2 diabetes. Utilizing data from a population at-risk for diabetes, the associations of LL with i) insulin resistance (IR) and beta-cell dysfunction and ii) a continuous metabolic syndrome risk score (MetScore) were analyzed. Results showed that shorter LL was associated with IR and beta-cell dysfunction, and that the combination of short legs and large waist (a marker of adult obesogenic conditions) was associated with the greatest IR. Height, a marker of overall childhood conditions, was found to be inversely associated with the MetScore. Therefore, both adverse childhood conditions and early-late life mismatched conditions may increase the risk for diabetes through differing pathways. Improving childhood conditions (i.e. nutritionally or economically) may be an important strategy to prevent diabetes.

The objective of this thesis was to determine the association of leg length (LL), a marker of early childhood conditions, with metabolic abnormalities underlying type 2 diabetes. Utilizing data from a population at-risk for diabetes, the associations of LL with i) insulin resistance (IR) and beta-cell dysfunction and ii) a continuous metabolic syndrome risk score (MetScore) were analyzed. Results showed that shorter LL was associated with IR and beta-cell dysfunction, and that the combination of short legs and large waist (a marker of adult obesogenic conditions) was associated with the greatest IR. Height, a marker of overall childhood conditions, was found to be inversely associated with the MetScore. Therefore, both adverse childhood conditions and early-late life mismatched conditions may increase the risk for diabetes through differing pathways. Improving childhood conditions (i.e. nutritionally or economically) may be an important strategy to prevent diabetes.

[Truncated abstract] Arachidonic acid is oxidised in vivo by non-enzymatic (free radical) or enzymatic pathways (cyclooxygenase, lipoxygenase, and cytochrome P450) to form a range of biologically active eicosanoids. Specifically, arachidonic acid is metabolised by cytochrome P450 -hydroxylase to produce vasoactive 20-hydroxyeicosatetraenoic acid (20-HETE), and by 5-lipoxygenase to produce proinflammatory leukotriene B4 (LTB4), which can further be metabolised by -hydroxylase to from 20-OH-LTB4 and 20-COOH-LTB4. F2-Isoprostanes (F2-IsoPs) are produced through free radical attack on arachidonic acid and have been recognised as the most reliable markers of lipid peroxidation in vivo. The metabolic syndrome (MetS) is characterised by abdominal obesity, hypertension, insulin resistance, glucose intolerance, and dyslipidemia. It is associated with low-grade inflammation and oxidative stress and an increased risk of developing cardiovascular diseases. Dietary weight loss is strongly recommended for the management of the MetS and can potentially minimise the risk of cardiovascular diseases and diabetes in individuals with the MetS. Little is known regarding the role of these arachidonic acid metabolites in the MetS and the effect of weight loss on their metabolism. Chapter three comprised of three in vitro studies aimed to examine 20-HETE synthesis in human blood cells. 20-HETE acts as a second messenger for vasoconstrictor actions of angiotensin II (Ang II) and endothelin-1 (ET-1) in renal and mesenteric beds. Human neutrophils and platelets are integral to the inflammatory process. ... Production of LTB4 and 20-OH-LTB4 was significantly lower compared with controls (P<0.005) and remained so after adjustment for neutrophil count (P<0.05).The weight loss intervention resulted in a 4.6kg reduction in body weight and a 6.6cm decrease in waist circumference and a significant increase in LTB4 and 20-OH- LTB4 in the weight loss group. Chapter Five continued to investigate the role of other arachidonic acid metabolites, 20-HETE and F2-IsoPs in the MetS and the effect of weight loss. In the case-control study (Human study 1), plasma and urinary 20-HETE and F2-IsoPs were significantly elevated in the MetS group, but no significant difference was found in stimulated-neutrophil 20-HETE. A significant gender x group interaction was observed in that women with the MetS had higher urinary 20-HETE and F2-IsoPs compared to controls (P<0.0001). In a randomised controlled trial (Human study 2), relative to the weight- maintenance group, a 4.6 kg loss in weight resulted in a 2 mmHg fall in blood pressure but did not alter the production of 20-HETE or F2-IsoPs. No significant differences were shown in 20-HETE released from stimulated-neutrophils before and after weight loss. 20-HETE and oxidative stress may be important mediators of cardiovascular disease risk in the MetS. Although a 4% reduction in body weight reduced BP, there were no changes in plasma or urinary 20-HETE or F2-IsoPs. In summary, in vitro studies show that human neutrophils and platelets can produce 20-HETE in response to Ang II and ET-1, and human studies demonstrate that the presence of MetS has a significant impact on arachidonic acid metabolism and effective weight loss can restore leukocyte synthesis of LTB4.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 6 uppsatser.

Disparities exist in the U.S. between the health status of African American and Hispanic individuals and the health status of non-Hispanic Caucasian individuals across all age groups. Those minority individuals age 55 and over are more likely to suffer from specific health disparities in areas such as diabetes, heart disease, and cancer than their white majority counterparts. Among the most common chronic disorders experienced within this age group are obesity, type II diabetes and cardiovascular disease, all three of which collectively form what has recently become known as metabolic syndrome. As of 2004, metabolic syndrome is diagnosable once criteria are clinically significant for a variety of different risk factors designated by the World Health Organization. However, like many syndromes these criteria are not stable across individuals, and leaves variability between individuals being diagnosed. It has been seen that each of the above mentioned racial/ethnic groups experience the individual risk factors at disproportionate rates, making it plausible that metabolic syndrome could be experienced in distinctly different ways depending upon racial/ethnic background. Using two nationally representative data sets, it is first largely evident that African American and Hispanic individuals are reaching higher peak rates of diabetes and cardiovascular disease much earlier in age than are non-Hispanic Caucasian individuals. The study goes on to reveals that the metabolic syndrome appears to follow one underlying progressive syndrome that begins with obesity and progresses towards heart disease. Each of the racial/ethnic groups experience significantly different progressions of the syndrome across time. Behavioral analysis found significant differences in health behaviors across the three groups; however a more pervasive lack of initiative in practicing preventive health behaviors is also present. The study achieved a higher understanding of individual differences within metabolic syndrome and insight into how and at what time in the lifespan health services can be most beneficial in providing preventive services to culturally diverse populations.

Thesis (M. Sc. (Physiology)) --University of Limpopo, 2019 / Introduction: There is an increased trend in the prevalence of hypertension in children and adolescents in African countries. There are complications in diagnosing hypertension in children and adolescents due to the variation of blood pressure (BP) values with age, gender and height. The progression of the health transition with non-communicable diseases (NCDs) adds significantly to the disease burden, despite infectious diseases and undernutrition remaining persistent in both low and middle-income countries. Metabolic syndrome (MetS) is a global problem associated with the clustering of several cardiovascular risk factors. South African evidence suggests an upsurge of NCDs amidst the existence of communicable diseases (CDs) such as HIV/AIDS and tuberculosis. Moreover, NCDs and CDs in the country are influenced by socio-demographic factors; and thus tend to be more prominent in certain segments of the population. Aim and Objectives: The aim of this study was to perform blood pressure to height ratio and to determine lifestyle risk factors associated with metabolic syndrome among the Ellisras rural population aged 6-30 years, who are part of the ELS. Methods and materials: The current study is based on secondary data analysis of the Ellisras Longitudinal Study (ELS) and was conducted in two phases. Phase 1 included data analysis of all the participants in the ELS. This sample included a total number of 9002 children and adolescents (4678 boys and 4324 girls), aged 6-17 years. Parents or guardians provided written informed consent. Phase 2 consisted of biochemical analysis from a subsample of participants in the ELS. The subsample included 624 participants (306 males and 318 females) aged 18-30 years at the time the study was conducted. All participants underwent a series of anthropometric measurements (waist circumference and height) according to the standard of the International Society for the Advancement of Kinanthropometry (ISAK). The waist circumference (WC) measurements were taken to the nearest 0.1 cm, using a soft measuring tape. Metabolic syndrome was defined according to the International Diabetes Federation (IDF) criteria. Metabolic syndrome risk factors included total cholesterol (TCHOL), triglycerides (TG), high-density lipoprotein cholesterol (HDLC), elevated fasting blood glucose (FBG), elevated blood pressure (BP) and high waist circumference (WC). A dietary intake questionnaire was also administered to each participant and self‑administered questionnaire was used to collect data on lifestyle factors, including smoking and alcohol intake. Dietary intake variables used in the linear regression method were log transformed prior to analysis because of their skewed distribution. Receiver-operating characteristic (ROC) curve was used to assess the accuracy of BPHR to screen children with prehypertension and hypertension. The optimal systolic BPHR (SBPHR) and diastolic BPHR (DBPHR) cut-off points for hypertension were determined. Sensitivity/specificity, positive predictive values and negative predictive values were calculated. Results: The optimal thresholds for defining prehypertension was 0.77 in children aged 6-10 years and 0.73 in adolescents aged between 11 and 17 years for systolic BPHR and 0.55 in children and 0.53 in adolescents for diastolic BPHR, respectively. The corresponding values for hypertension stage 1 were 0.76 and 0.73 for SBPHR and 0.50 and 0.58 for DBPHR, respectively. The BPHR is an accurate tool for screening elevated BP in Ellisras children aged 6-17 years. This can help to prevent the misclassification of children and adolescent hypertension. Furthermore, this tool can be used to screen children before the development of prehypertension and hypertension. Moreover, it can be used to manage hypertension in Ellisras children, ultimately reducing the risks of developing hypertension and associated cardiovascular disease in adulthood. Overall, the prevalence of metS was 23.1% (8.6% males and 36.8% females). Females appeared to have higher mean values for WC, FBG, TCHOL and LDL-C than males (82.14, 5.62, 4.62 and 2.97, respectively). The only significant gender difference observed was on WC (p<0.001). Males on the other hand had higher mean values for HDL-C, TG, SBP and DBP than females (1.20, 1.06, 125.91 and 71.44, respectively). The only significant difference observed in this case was on SBP (p<0.001). No significant age group differences were observed in all the metabolic risk factors with the exception of DBP where the older (25-30 years) participants presented with high SBP than the younger age group (18-24 years) (70.96 mmHg vs 68.78 mmHg, p<0.05). While, majority of females had significantly high WC, elevated total cholesterol and LDL-C, and reduced HDL-C; majority of males had elevated BP, SBP and DBP. No significant age and gender differences were observed on dietary intake. However, according to the linear regression analysis, no association between log total energy, log added sugar, log SFA and log MUFA with metabolic risk factors. There was a low and negative significant association between log fibre with SBP and DBP (β:-0.004, p=0.003 and β:-0.004, p=0.046), respectively, crude. After adjusting for the potential confounding factors, log fibre was also associated with FBG (β:-0.028, p=0.046). Log PUFAs was inversely associated with FBG, HDL-C and SBP crude. Log trans fatty acids was inversely associated with WC, HDL-C and SBP crude. Both log PUFAs and log trans fatty acids were not associated with any metabolic risk factors after adjusting for potential cofounding factors. Log protein was inversely associated with SBP both crude and adjusted for potential cofounding factors. On predicting the actual risk using the logistic regression analysis, participants who had high dietary energy intake were significantly less likely to present with larger WC, low HDL-C and high LDL-C (OR: 0.250 95%CI [0.161;0.389], OR: 0.306 95%CI [0.220;0.425] and OR: 0.583 95%CI [0.418;0.812], respectively), but more likely to presents with elevated FBG, high TCHOL, high TG and hypertension (OR: 1.01 95%CI [0.735;1.386], OR: 1.039 95%CI [0.575;1.337], OR: 1.186 95%CI [0.695;2.023], OR: 5.205 95%CI [3.156;8.585], respectively) crude. After adjusting for age, gender, smoking and alcohol status, high energy intake was more likely to increase two times high the large WC and elevated FBG among study participants (OR: 2.766 95%CI [0.863;3.477] and OR: 2.227 95%CI [1.051;3.328], respectively). Furthermore, low dietary fibre intake was nearly four times more likely to increase the low HDL-C, crude (OR: 3.864 95%CI [1.067;13.988]) crude. Those participants who consumed high trans fats were more likely to present with high FBG (OR:1.424 95%CI [0.985;2.060]), but less likely to present with LDL-C (OR: 0.540 95%CI [0.321;0.906]) crude. However, after adding potential cofounding factors, participants with high fatty acid were less likely to present with high FBG (OR: 0.672 95%CI [0.441;1.023]). Conclusions: MetS is prevalent in young adults in Ellisras and is differentiated by age and gender with more females at an increased rate by virtue of their body size status, reduced HDL-C, elevated FBG and high LDL-C and the diet they consume that is in most cases high energy, more carbohydrates, high added sugar and SFA. Therefore, identifying groups that are at an increased risk and those that are in their early stages of MetS will help improve and prevent the increase of the metS in the future. These results have high policy implications. KEY CONCEPTS Metabolic syndrome; risk factors; blood pressure; blood pressure to height ratio; cardiovascular disease; dietary intake; rural South African.

Thesis (M. A. (Physiology)) -- University of Limpopo, 2022 / Background: Metabolic syndrome (MetS) is amongst the underlying causes of mortality and morbidity globally. However, lifestyle habits such as frequent consumption of sugar-sweetened beverages (SSBs) contributes to its onset. The study was aimed at investigating the association between MetS and SSBs intake among Ellisras rural youth. Additionally, to find the best obesity indices to predict MetS. Methods: The current study included a total of 593 Ellisras rural youth, aged 22 to 30 years (289 males and 304 females). Anthropometric measurements, blood pressure (BP), and biochemical assessment were taken using standards procedures. A validated 24hrs recall questionnaire and food manuals were used to collect SSBs data. Binary logistic regression was applied to determine the association between SSBs intake and MetS components for the adjusted model. Confirmatory factor analysis was used to test the best single-factor models to predict MetS on commonly selected obesity indices. Results: The SSBs quartile 4 was associated with a high risk of high fasting blood glucose (FBG) for adjusted (OR=2.32; CI=1.15-4.70; p<0.05) and unadjusted (OR=2.34; CI=1.16-4.73; p<0.05) models were a significant linear trend (p for trend=0.049) in males was found. Low risk of reduced high density lipoprotein cholesterol (HDL-C) was associated with the second and fourth SSBs quartiles for unadjusted ((OR=0.40; CI=0.18-0.85; p<0.05; OR=0.37; CI=0.13-0.80; p<0.05) respectively and adjusted model (OR=0.40; CI=0.18-0.85; p<0.05; OR=0.37; CI=0.17-0.80; p<0.05) respectively in females. Moreover, the fourth SSBs quartile was likely to decrease the risk of high triglycerides (TG) for unadjusted (OR=0.12; CI=0.01-0.87; p<0.05) and adjusted (OR=0.10; CI=0.01-0.83; p<0.05) models were the significant linear trend (p= trend 0.006) was observed also in females. There was a significant linear trend association between SSBs quartiles consumption and high TG in males and high waist circumference (WC) in females, but logistic regression analysis didn’t depict any significant association (p>0.05). In males, single model fit built based on WC (comparative fit index (CFI)=1.00; turker lewis index (TLI)=1.05; RMSEA=0.00; akaike information criterion (AIC)=-2680) and waist to height ratio v (WHtR) (RMSEA=0.00, CFI=1.00; AIC=-2662, TLI=1.05;) suggested a better fit index as compared to body mass index (BMI) and neck circumference (NC). Among females, a single model fit built on NC obtained a better fit index (RMSEA=0.05, CFI=0.90, and AIC= -429.21, TLI=0.71). Conclusion: In this study, there was an association between SSBs consumption and some MetS components (high TG, reduced HDL-C, and high FBG). Obesity indices including WHtR, NC, and WC were the best predictors of MetS. Future studies are recommended to further investigate the association of the risk of MetS and the consumption SSBs and the best obesity indices to predict MetS to assist in efforts to help curb MetS and related risk factors in rural areas of South Africa.

Background In South Africa, as in many other developing countries, obesity has become a major health problem causing an increase in the incidence and prevalence of various non-communicable diseases. Research has shown that excess adiposity is associated with low vitamin D status and detrimental to bone health. Low vitamin D status has been linked to various non-communicable diseases which includes osteoporosis, and also the metabolic syndrome. Information is scarce on the role of lean mass and fat mass on bone health in the black South African population. There is also a shortage of data on the association between vitamin D status and the metabolic syndrome in the South African population. Aim The main aim of this study was to examine factors (vitamin D status, socio-economic status [SES] and lifestyle risk factors) associated with body composition, including bone health, as well as predictors of change in body composition in African adults in the North West Province of South Africa. Methods The first study that forms part of this thesis was a longitudinal study aimed at examining the effects of urbanization, socio-economic status and lifestyle factors on changes in body composition over 5 years in rural and urban black South African adults. A total of 1058 men and women above age 30 years from the Prospective Urban Rural Epidemiology study were included in this study. The second study to form part of this thesis aimed to examine the association between body composition and bone health in urban black South African women. Structured questionnaires were used to collect socio-demographic and lifestyle information including medication and tobacco use. This second study is cross-sectional in design and it included 189 postmenopausal women aged > 43 years old. Dual X-ray absorptiometry was used to assess bone mineral density, lean mass and fat mass, while structured and specific questionnaires were used to assess the habitual physical activity, food frequency and fracture risk. Habitual activity energy expenditure was also measured using an accelerometer with a combined heart rate monitor. The third study aimed to examine the association of serum 25 hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentration, respectively, with the metabolic syndrome while controlling for adiposity in black women in the North West Province, South Africa. This third study is also cross-sectional in design and it included 209 HIV-negative urban women. Dual X-ray absorptiometry was used to assess adiposity, while habitual physical activity was accessed with questionnaire and habitual activity energy expenditure was also measured using an accelerometer with a combined heart rate monitor. Results Study 1: Over a 5-year period, body mass index (BMI) and waist circumference increased in both genders, but the change was significant for BMI (P<0.01) and waist circumference (P<0.001) in women only, indicating an increase in adiposity over time. Urban residency positively predicted changes in waist circumference in men (p < 0.05) and women (p < 0.001) as well as change in triceps skinfold thickness of men (p < 0.05). Being married positively predicted changes in BMI (p < 0.001) and waist circumference (p < 0.001) in men, while age negatively predicted changes in triceps skinfold thickness in women (p < 0.001). Study 2: Fat mass and lean mass were significantly positively associated with bone mineral density (BMD) and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = -0.19 p =0.04) when both lean and fat mass were in the same model. Study 3: After adjusting for age, body fat, habitual physical activity, tobacco use and season, neither 25(OH)D nor PTH concentrations showed significant associations with having the metabolic syndrome. However, when body fat was replaced with waist circumference there was a weak positive association between 25(OH)D concentration and the metabolic syndrome. No significant association was found between PTH:25(OH)D ratio and the metabolic syndrome. Conclusion This thesis has highlighted that the prevalence of obesity among black South Africans is high particularly among women and urbanization played a significant role in the increasing adiposity of black South Africans in the North West province. Lean mass had a stronger association with bone health in comparison to fat mass in urban black South African women. Low 25(OH)D concentration was not associated with the metabolic syndrome while there was no significant association between PTH and the metabolic syndrome in our black South African women. / PhD (Dietetics), North-West University, Potchefstroom Campus, 2015

Background In South Africa, as in many other developing countries, obesity has become a major health problem causing an increase in the incidence and prevalence of various non-communicable diseases. Research has shown that excess adiposity is associated with low vitamin D status and detrimental to bone health. Low vitamin D status has been linked to various non-communicable diseases which includes osteoporosis, and also the metabolic syndrome. Information is scarce on the role of lean mass and fat mass on bone health in the black South African population. There is also a shortage of data on the association between vitamin D status and the metabolic syndrome in the South African population. Aim The main aim of this study was to examine factors (vitamin D status, socio-economic status [SES] and lifestyle risk factors) associated with body composition, including bone health, as well as predictors of change in body composition in African adults in the North West Province of South Africa. Methods The first study that forms part of this thesis was a longitudinal study aimed at examining the effects of urbanization, socio-economic status and lifestyle factors on changes in body composition over 5 years in rural and urban black South African adults. A total of 1058 men and women above age 30 years from the Prospective Urban Rural Epidemiology study were included in this study. The second study to form part of this thesis aimed to examine the association between body composition and bone health in urban black South African women. Structured questionnaires were used to collect socio-demographic and lifestyle information including medication and tobacco use. This second study is cross-sectional in design and it included 189 postmenopausal women aged > 43 years old. Dual X-ray absorptiometry was used to assess bone mineral density, lean mass and fat mass, while structured and specific questionnaires were used to assess the habitual physical activity, food frequency and fracture risk. Habitual activity energy expenditure was also measured using an accelerometer with a combined heart rate monitor. The third study aimed to examine the association of serum 25 hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) concentration, respectively, with the metabolic syndrome while controlling for adiposity in black women in the North West Province, South Africa. This third study is also cross-sectional in design and it included 209 HIV-negative urban women. Dual X-ray absorptiometry was used to assess adiposity, while habitual physical activity was accessed with questionnaire and habitual activity energy expenditure was also measured using an accelerometer with a combined heart rate monitor. Results Study 1: Over a 5-year period, body mass index (BMI) and waist circumference increased in both genders, but the change was significant for BMI (P<0.01) and waist circumference (P<0.001) in women only, indicating an increase in adiposity over time. Urban residency positively predicted changes in waist circumference in men (p < 0.05) and women (p < 0.001) as well as change in triceps skinfold thickness of men (p < 0.05). Being married positively predicted changes in BMI (p < 0.001) and waist circumference (p < 0.001) in men, while age negatively predicted changes in triceps skinfold thickness in women (p < 0.001). Study 2: Fat mass and lean mass were significantly positively associated with bone mineral density (BMD) and fracture risk when adjusted for potential confounders. However, lean mass and not fat mass remained significantly associated with femoral neck BMD (β = 0.49, p <0.001), spine BMD (β = 0.48, p< 0.0001) and hip BMD (β = 0.59, p< 0.0001). Lean mass was also negatively associated with fracture risk (β = -0.19 p =0.04) when both lean and fat mass were in the same model. Study 3: After adjusting for age, body fat, habitual physical activity, tobacco use and season, neither 25(OH)D nor PTH concentrations showed significant associations with having the metabolic syndrome. However, when body fat was replaced with waist circumference there was a weak positive association between 25(OH)D concentration and the metabolic syndrome. No significant association was found between PTH:25(OH)D ratio and the metabolic syndrome. Conclusion This thesis has highlighted that the prevalence of obesity among black South Africans is high particularly among women and urbanization played a significant role in the increasing adiposity of black South Africans in the North West province. Lean mass had a stronger association with bone health in comparison to fat mass in urban black South African women. Low 25(OH)D concentration was not associated with the metabolic syndrome while there was no significant association between PTH and the metabolic syndrome in our black South African women. / PhD (Dietetics), North-West University, Potchefstroom Campus, 2015