BMI in Women With and Without PCOS
BMI in Women With and Without PCOS
Study Question What is the contribution of diet, physical activity and sedentary behaviour to body mass index (BMI) in women with and without polycystic ovary syndrome (PCOS)?
Summary Answer PCOS status, higher energy intake and glycaemic index and lower physical activity were independently associated with BMI.
What is Known Already Obesity worsens the clinical features of PCOS and women with PCOS have an elevated prevalence of overweight and obesity. It is not known whether there is a contribution of lifestyle factors such as dietary intake, physical activity or sedentary behaviour to the elevated prevalence of obesity in PCOS.
Study Design, Size, Duration This study is a population-based observational study with data currently collected at 13 year follow-up. The study commenced in 1996. For this analysis, data are analysed at one time point corresponding to the Survey 5 of the cohort in 2009. At this time 8200 participants remained (58% retention of baseline participants) of which 7466 replied to the questionnaire; 409 self-reported a diagnosis of PCOS and 7057 no diagnosis of PCOS.
Participants/Materials, Setting, Methods Australian women born in 1973–1978 from the Australian Longitudinal Study on Women's Health.
Main Results and the Role of Chance Mean BMI was higher in women with PCOS compared with non-PCOS (29.3 ± 7.5 versus 25.6 ± 5.8 kg/m, P < 0.001). Women with PCOS reported a better dietary intake (elevated diet quality and micronutrient intake and lower saturated fat and glycaemic index intake) but increased energy intake, increased sitting time and no differences in total physical activity compared with non-PCOS. PCOS status, higher energy intake and glycaemic index and lower physical activity, as well as age, smoking, alcohol intake, occupation, education and country of birth, were independently associated with BMI.
Limitations, Reasons for Caution The weaknesses of this study include the self-reported diagnosis of PCOS, and the women not reporting PCOS not having their control status clinically verified which is likely to underrepresent the PCOS population. We are also unable to determine if lifestyle behaviours contributed to the PCOS diagnosis or were altered in response to diagnosis.
Wider Implications of The Findings The strengths of this study include the community-based nature of the sample which minimizes selection bias to include women with a variety of clinical presentations. These results are therefore generalizable to a broader population than the majority of research in PCOS examining this research question which are performed in clinic-based populations. This study is in agreement with the literature that PCOS is independently associated with elevated BMI. We provide new insights that diet quality is subtly improved but that sedentary behaviour is elevated in PCOS and that PCOS status, higher energy intake and glycaemic index and lower physical activity are independently associated with BMI.
Study Funding/Competing Interest(S) L.J.M. was supported by a South Australian Cardiovascular Research Development Program (SACVRDP) Fellowship (AC11S374); a program collaboratively funded by the National Heart Foundation of Australia, the South Australian Department of Health and the South Australian Health and Medical Research Institute, S.A.M. was funded by an Australian Research Council Future Fellowship (FT100100581), S.Z. was funded by a Heart Foundation Career Development Fellowship (ID CR10S5330) and H.J.T. was funded by an NHMRC fellowship (ID 545888). None of the authors has any conflict of interest to declare.
Trial Registration Number Not applicable.
Polycystic ovary syndrome (PCOS) affects up to 18% of reproductive-aged women (March et al., 2010) and is associated with reproductive (hyperandrogenism, menstrual irregularity, anovulation, infertility, pregnancy complications), metabolic (elevated risk factors for type 2 diabetes mellitus and cardiovascular disease and elevated prevalence of type 2 diabetes mellitus and cardiovascular disease) and psychological characteristics (worsened quality of life and elevated prevalence of anxiety and depression; Teede et al., 2011). Insulin resistance is a pathophysiological feature of PCOS and is proposed to be mechanistically distinct (or intrinsic) from obesity-associated insulin resistance. Insulin resistance present in the majority of women with PCOS, including lean women (Dunaif et al., 1989), and worsens the clinical presentation. Weight gain further compounds insulin resistance (Erdmann et al., 2008). Given the association between insulin resistance, obesity and the presentation of PCOS, weight management is a key initial treatment strategy for PCOS (Teede et al., 2011) and improves the reproductive, metabolic and psychological features (Moran et al., 2011).
There is emerging evidence that women with PCOS have an elevated risk of being overweight and obese and have increased longitudinal weight gain compared with community controls (Teede et al., 2013). A recent meta-analysis has reported increased prevalence of overweight or obesity [1.95 risk ratio; 95% confidence interval (CI) 1.52–2.50] for women with PCOS compared with controls (Lim et al., 2012). We have proposed that there is a bidirectional interaction between PCOS and weight with PCOS driving weight gain and weight gain contributing to an increased prevalence and severity of PCOS (Teede et al., 2013). Indeed, women with PCOS may have specific physiological or intrinsic barriers to maintaining a healthy weight such as insulin resistance, hyperinsulinaemia and hyperandrogenism, which can contribute to weight or abdominal fat gain (1988, Pasquali, 2006), reduce energy expenditure and increase food intake (Felig, 1984; Welle et al., 1988; Franssila-Kallunki and Groop, 1992; Robinson et al., 1992; Carlson and Campbell, 1993; Kersten, 2001; Moran et al., 2004; Hirschberg et al., 2004; Georgopoulos et al., 2008; Ryan et al., 2008). Women with PCOS may additionally have altered energy balance caused by extrinsic factors, supported by reports of reduced physical activity (Eleftheriadou et al., 2012) and increased intake of high glycaemic index foods compared with controls (Douglas et al., 2006). Conversely, other research suggest no differences in energy or dietary intake such as macronutrient, micronutrient or food group intake, physical activity or muscle strength between lean or overweight women with or without PCOS (Wright et al., 2004; Douglas et al., 2006; Thomson et al., 2009).
Given the prevalence and health burden of PCOS and the propensity to, and adverse impact of excess weight in PCOS, it is important to explore potentially modifiable extrinsic or environmental factors that may contribute to obesity in women with PCOS to guide management. The aim of this study was to examine the association of demographic variables and extrinsic factors, including diet and physical activity, with body mass index (BMI) in a large community study of women with and without diagnosed PCOS.
Abstract and Introduction
Abstract
Study Question What is the contribution of diet, physical activity and sedentary behaviour to body mass index (BMI) in women with and without polycystic ovary syndrome (PCOS)?
Summary Answer PCOS status, higher energy intake and glycaemic index and lower physical activity were independently associated with BMI.
What is Known Already Obesity worsens the clinical features of PCOS and women with PCOS have an elevated prevalence of overweight and obesity. It is not known whether there is a contribution of lifestyle factors such as dietary intake, physical activity or sedentary behaviour to the elevated prevalence of obesity in PCOS.
Study Design, Size, Duration This study is a population-based observational study with data currently collected at 13 year follow-up. The study commenced in 1996. For this analysis, data are analysed at one time point corresponding to the Survey 5 of the cohort in 2009. At this time 8200 participants remained (58% retention of baseline participants) of which 7466 replied to the questionnaire; 409 self-reported a diagnosis of PCOS and 7057 no diagnosis of PCOS.
Participants/Materials, Setting, Methods Australian women born in 1973–1978 from the Australian Longitudinal Study on Women's Health.
Main Results and the Role of Chance Mean BMI was higher in women with PCOS compared with non-PCOS (29.3 ± 7.5 versus 25.6 ± 5.8 kg/m, P < 0.001). Women with PCOS reported a better dietary intake (elevated diet quality and micronutrient intake and lower saturated fat and glycaemic index intake) but increased energy intake, increased sitting time and no differences in total physical activity compared with non-PCOS. PCOS status, higher energy intake and glycaemic index and lower physical activity, as well as age, smoking, alcohol intake, occupation, education and country of birth, were independently associated with BMI.
Limitations, Reasons for Caution The weaknesses of this study include the self-reported diagnosis of PCOS, and the women not reporting PCOS not having their control status clinically verified which is likely to underrepresent the PCOS population. We are also unable to determine if lifestyle behaviours contributed to the PCOS diagnosis or were altered in response to diagnosis.
Wider Implications of The Findings The strengths of this study include the community-based nature of the sample which minimizes selection bias to include women with a variety of clinical presentations. These results are therefore generalizable to a broader population than the majority of research in PCOS examining this research question which are performed in clinic-based populations. This study is in agreement with the literature that PCOS is independently associated with elevated BMI. We provide new insights that diet quality is subtly improved but that sedentary behaviour is elevated in PCOS and that PCOS status, higher energy intake and glycaemic index and lower physical activity are independently associated with BMI.
Study Funding/Competing Interest(S) L.J.M. was supported by a South Australian Cardiovascular Research Development Program (SACVRDP) Fellowship (AC11S374); a program collaboratively funded by the National Heart Foundation of Australia, the South Australian Department of Health and the South Australian Health and Medical Research Institute, S.A.M. was funded by an Australian Research Council Future Fellowship (FT100100581), S.Z. was funded by a Heart Foundation Career Development Fellowship (ID CR10S5330) and H.J.T. was funded by an NHMRC fellowship (ID 545888). None of the authors has any conflict of interest to declare.
Trial Registration Number Not applicable.
Introduction
Polycystic ovary syndrome (PCOS) affects up to 18% of reproductive-aged women (March et al., 2010) and is associated with reproductive (hyperandrogenism, menstrual irregularity, anovulation, infertility, pregnancy complications), metabolic (elevated risk factors for type 2 diabetes mellitus and cardiovascular disease and elevated prevalence of type 2 diabetes mellitus and cardiovascular disease) and psychological characteristics (worsened quality of life and elevated prevalence of anxiety and depression; Teede et al., 2011). Insulin resistance is a pathophysiological feature of PCOS and is proposed to be mechanistically distinct (or intrinsic) from obesity-associated insulin resistance. Insulin resistance present in the majority of women with PCOS, including lean women (Dunaif et al., 1989), and worsens the clinical presentation. Weight gain further compounds insulin resistance (Erdmann et al., 2008). Given the association between insulin resistance, obesity and the presentation of PCOS, weight management is a key initial treatment strategy for PCOS (Teede et al., 2011) and improves the reproductive, metabolic and psychological features (Moran et al., 2011).
There is emerging evidence that women with PCOS have an elevated risk of being overweight and obese and have increased longitudinal weight gain compared with community controls (Teede et al., 2013). A recent meta-analysis has reported increased prevalence of overweight or obesity [1.95 risk ratio; 95% confidence interval (CI) 1.52–2.50] for women with PCOS compared with controls (Lim et al., 2012). We have proposed that there is a bidirectional interaction between PCOS and weight with PCOS driving weight gain and weight gain contributing to an increased prevalence and severity of PCOS (Teede et al., 2013). Indeed, women with PCOS may have specific physiological or intrinsic barriers to maintaining a healthy weight such as insulin resistance, hyperinsulinaemia and hyperandrogenism, which can contribute to weight or abdominal fat gain (1988, Pasquali, 2006), reduce energy expenditure and increase food intake (Felig, 1984; Welle et al., 1988; Franssila-Kallunki and Groop, 1992; Robinson et al., 1992; Carlson and Campbell, 1993; Kersten, 2001; Moran et al., 2004; Hirschberg et al., 2004; Georgopoulos et al., 2008; Ryan et al., 2008). Women with PCOS may additionally have altered energy balance caused by extrinsic factors, supported by reports of reduced physical activity (Eleftheriadou et al., 2012) and increased intake of high glycaemic index foods compared with controls (Douglas et al., 2006). Conversely, other research suggest no differences in energy or dietary intake such as macronutrient, micronutrient or food group intake, physical activity or muscle strength between lean or overweight women with or without PCOS (Wright et al., 2004; Douglas et al., 2006; Thomson et al., 2009).
Given the prevalence and health burden of PCOS and the propensity to, and adverse impact of excess weight in PCOS, it is important to explore potentially modifiable extrinsic or environmental factors that may contribute to obesity in women with PCOS to guide management. The aim of this study was to examine the association of demographic variables and extrinsic factors, including diet and physical activity, with body mass index (BMI) in a large community study of women with and without diagnosed PCOS.
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