Rev Bras Fisiol Exerc. 2023;22:e225513

doi: 10.33233/rbfex.v22i1.5513

REVIEW

Polycystic ovary syndrome: relation with diet and exercise - systematic review of randomized clinical trials

Síndrome dos ovários policísticos: relação com dieta e exercício - revisão sistemática de ensaios clínicos randomizados

 

Marina Amorim Santos1, Nathália Rocha Rios Mendes Machado1, Paulo Gabriel Barbosa de Carvalho1, Márcia Farias Moreira1, Francisco Paulo Cerqueira Mota1

 

1Centro Universitário UniFTC, Salvador, BA, Brazil

 

Received: May 4, 2023; Accepted: July 18, 2023.

Correspondence: Marina Amorim Santos, marinaamorimsantos@hotmail.com

 

How to cite

Santos MA, Machado NRRM, Carvalho PGB, Moreira MF, Mota FPC. Polycystic ovary syndrome: relation with diet and exercise – systematic review of randomized clinical trials. Ver Bras Fisiol Exerc. 2023;22:e225513. doi: 10.33233/rbfex.v22i1.5513

 

Abstract

Introduction: Women with polycystic ovary syndrome tend to present overweight/obese and have worst results for reproduction. Knowing that the effects of weight loss have a positive factor in the prognosis of fertility, the summary of published articles about the changes of lifestyle modification has on ovulation/pregnancy is important for health professionals to reinforce the method as a first-line therapeutic strategy. Aim: This study aimed to describe the alterations of lifestyle modifications on ovulation/pregnancy in overweight/obese women with polycystic ovary syndrome. Methods: It is a systematic review of randomized clinical trials based on the Preferred Reporting Items guideline for Systematic Review and Meta-analyses (PRISMA). Publications between 2010-2021 in Portuguese or English in databases: Pubmed, Scielo, and Lilacs were included. The interest variables analyzed were: age, body mass index, lifestyle modification, comorbidities, and reproductive outcome (ovulation/pregnancy). Results: 15 studies were screened through the databases, and four were manually accessed through the reference list of the selected articles. After analyzing the eligibility criteria, five studies were considered relevant and included in this review, all randomized clinical trials. Conclusion: The lifestyle modification treatment implementation of overweight/obese women with polycystic ovary syndrome improved ovulation rate and menstrual regularity.

Keywords: obesity; infertility; healthy lifestyle.

 

Resumo

Introdução: Mulheres portadoras da Síndrome dos Ovários Policísticos apresentam maior tendência a sobrepeso/obesidade e piores resultados no desfecho reprodutivo. Sabendo que os efeitos da perda de peso possuem fator positivo no prognóstico da fertilidade, a síntese de estudos sobre a mudança no estilo de vida na ovulação é importante para que os profissionais de saúde a reforcem como estratégia terapêutica de primeira linha. Objetivo: O presente estudo teve como objetivo descrever as alterações que a mudança no estilo de vida tem na ovulação/gestação em mulheres com sobrepeso/obesidade portadoras de síndrome dos ovários policísticos. Métodos: Trata-se de uma revisão sistemática da literatura de ensaios clínicos randomizados baseada nos critérios do Preferred Reporting Items guideline for Systematic Review and Meta-analyses (PRISMA). Foram incluídas publicações entre 2010 e 2021, em português e inglês, presentes nas bases de dados: Pubmed, Scielo e Lilacs. As variáveis de interesse analisadas foram: idade, índice de massa corporal, mudança de estilo de vida, comorbidades e desfecho reprodutivo (ovulação/gestação). Resultados: Foram triados 15 estudos pela base de dados e 4 foram acessados manualmente através da lista de referências dos artigos selecionados. Após análise dos critérios de elegibilidade, 5 ensaios clínicos randomizados foram considerados relevantes e incluídos nesta revisão. Conclusão: A implementação da mudança do estilo de vida no tratamento de mulheres com sobrepeso/obesidade portadoras de síndrome dos ovários policísticos demonstrou resultados satisfatórios no desfecho ovulação, com melhora das taxas e regularidade menstrual.

Palavras-chave: obesidade; infertilidade; estilo de vida saudável.

 

Introduction

 

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects about 10% of women of reproductive age worldwide [1]. Patients with this condition have a heterogeneous disorder [2] characterized by dysfunction in the neuro-endocrine-reproductive axis, which leads to ovarian morphological alteration and high androgen production [3], which predisposes to the development of metabolic and non-metabolic systemic disorders that go far beyond infertility.

Women with PCOS who manage to become pregnant, for example, have a high rate of early miscarriage (30 to 50%) compared to the average rate in the general population, which is 15% [4]. In addition, they are at increased risk of pregnancy complications, including gestational diabetes and hypertensive disorders, which ultimately result in preterm labor and perinatal mortality [5,6].

Among the causes of infertility and gestational complications related to PCOS, it is known that pre-gestational overweight and obesity are relevant as aggravating negative factors, with a higher body mass index (BMI) being associated with a worse fertility prognosis, regardless of the mode of conception [5,6,7]. On the other hand, it has been shown that weight loss improves reproduction and metabolism rates [8,9,10]. Thus, lifestyle modification (LSM), i.e., a healthy diet and physical activity, has been recommended as a first-line strategy before any intervention for women with PCOS and reproductive desire [11,12,13].

Although several studies address different therapeutic options for patients with PCOS, a comparison between the already available studies that discuss the implementation of LSM as a therapeutic strategy is important for the synthesis of the most current information on its impact on ovulation/gestation. This facilitates the access of health professionals to this topic, who, in addition to detecting, preventing, and treating risk factors at an early stage in overweight/obese patients with PCOS, will be more able to instruct them about the practice of exercises daily physical exercises and food re-education.

Therefore, this study aimed to describe the changes that lifestyle modifications have on ovulation/gestation in overweight/obese patients with polycystic ovary syndrome.

 

Methods

 

This study is a systematic review of the literature based on the criteria of the Preferred Reporting Items guideline for Systematic Review and Meta-analyses (PRISMA) [14] and registered in PROSPERO under id: CRD42023421853. To this end, original articles were selected, including randomized clinical trials published between 2010 and 2021, in Portuguese and English, found registered in the following databases: Pubmed, Scielo, and Lilacs, which gathered the available evidence on the alterations that lifestyle modification has on ovulation/pregnancy in overweight/obese patients with polycystic ovary syndrome.

Studies whose intervention method was only drugs that induce ovulation, as well as studies focused exclusively on obesity and infertility, were excluded. Conference abstracts and unpublished manuscripts were considered ineligible.

 

Sample eligibility criteria

 

Women of reproductive age, aged between 18 and 40 years, with a BMI ≥ 25 kg/m2, infertile due to PCOS, submitted to programs composed of exercises and/or diet, were included in the sample, and no specific definition of exercise or diet was used in the search strategy to include as many studies as possible.

 

Study search and selection strategy

 

The search strategy included the descriptors and the respective terms translated into Portuguese found in DeCS/MeSH: Polycystic Ovary Syndrome, Obesity, Ovulation, Pregnancy, Exercise and Diet, and Healthy, which were used together through Boolean operators (AND) to identify the appropriate articles.

Other articles that met the eligibility criteria were manually searched through the reference list of eligible studies.

 

Data summary

 

The studies were sorted by title by the authors and were analyzed by abstract to see if they met the inclusion criteria. Duplicate articles were removed manually. Those that did not meet the criteria were excluded, and the approved ones were analyzed in full for data extraction that sought information about the sample, intervention protocol (diet and/or physical exercise), and measurement of ovulation and pregnancy, including pregnancy complications. All authors participated in the stage, and disagreements about the selection and/or extraction of data were discussed among them.

 

Quality of evidence and risk of bias

 

The risk of bias in each study was ascertained using the Downs and Black Risk of Bias tool [15]. It was evaluated by all the authors. And, in case of disagreement, the finding of the majority prevailed. This tool is an accurate checklist that provides an overall score for study quality and is appropriate for evaluating randomized and non-randomized studies.

 

Results

 

Nineteen studies were identified according to the proposed methodological strategy. After applying the eligibility criteria, five articles were included in this review, all randomized clinical trials. Figure 1 shows the selection of articles.

 

 

RCT = randomized controlled trial; PCOS = Polycystic Ovary Syndrome

Figure 1 – Flowchart of article selection

 

The samples of the selected studies ranged from 49 to 577 participants, totaling 928 individuals. The target population studied was overweight/obese infertile women with PCOS, BMI ≥ 25 kg/m2, aged 18-40 years. Regarding the intervention, although all the articles used the LSM through physical activity and/or diet, the dietary and exercise strategy used differed between the studies, each one presenting particularities. This information is more detailed in Table I. Para avaliar a qualidade das evidências e risco de viés dos estudos incluídos na síntese qualitativa foi utilizada a escala de Downs and Black [15] (Table I). To assess the evidence quality and risk of bias in the studies included in the qualitative synthesis, the Downs and Black scale [15] was used (Chart 1).

 

Table I - Qualitative synthesis of selected articles

 

Chart 1 – Quality of evidence according to the Downs and Black scale [15]

 

Discussion

 

This review showed that the lifestyle modifications implemented in the treatment of women with PCOS significantly improved the evaluated ovulatory patterns, especially when associated with drug treatment. Soon, it was found that the ovulation rate and the regularity of menstrual cycles were higher when the intervention had LSM involved.

It appears that ovulation is influenced by obesity due to a hormonal imbalance, the main one being insulin resistance [22]. Previous studies have already proven the relationship between insulin signaling and steroidogenesis through therapeutic interventions with insulin sensitizers, which, when implemented, reduced total and free androgen concentrations and increased SHBG (sex hormone-binding globulin) [8].

Interestingly, these same changes were observed with weight loss [23] and physical activity practice, as this is effective in restoring ovulation, regardless of the decrease in BMI [24]. This happens because exercise alone can modulate inflammatory proteins with a negative effect on the insulin signal even when it does not cause weight change [25].

Thus, submitting patients with PCOS, who tend to accumulate visceral adipose tissue for reasons that are still unclear, to a routine of physical exercises and a healthy diet allows the restoration of the hormonal pattern and, consequently, the improvement of the reproductive outcome. In this regard, the studies' results reviewed here are consistent with the literature published.

As for the percentage of clinical pregnancy detected, the studies evaluated did not report relevant differences concerning the conception rate between the observed groups, except for Sim et al. [20], who demonstrated a higher pregnancy rate in the group submitted to lifestyle changes. Furthermore, in terms of gestational complications, considerable differences between the analyzed groups were also not observed in most studies, showing that, at least in these cases, LSM has little or no significant impact.

According to the existing literature, unfavorable gestational outcomes are distinguished according to the characteristics of PCOS [26] and occur independently of obesity [27]. Thus, during pregnancy, there is an increase in adverse outcomes in women with PCOS compared to women without this syndrome, with the most cited being gestational diabetes mellitus, preeclampsia, premature birth, and poor perinatal outcomes [26,27]. Similar results, however, were not found in the present study.

Regarding the limitations of this review, it is worth mentioning the non-standardization of the interventions carried out since, in an attempt to include a higher number of studies, no specific definition of LSM was used. Furthermore, the selected studies were performed with a relatively small sample of patients. It is also important to highlight that in this present study, as well as in the scientific evidence available on this subject, the mechanisms by which physical activity and diet influence the reproductive outcome in PCOS were not fully clarified. As a result, it is necessary to continue research on this subject.

The highlight of this review is due to the most recent information regarding lifestyle changes and PCOS that were condensed in this study and the scarcity of articles focused on this topic, in addition to the selectivity of the bibliographic research carried out, including only randomized clinical trials to increase the level of scientific evidence.

 

Conclusion

 

The implementation of lifestyle modifications in the treatment of overweight/obese women with PCOS has shown satisfactory results in the ovulation outcome, with improved rates and menstrual regularity.

 

Academic affiliation

This article represents the course completion work of Marina Amorim Santos, Nathália Rocha Rios Mendes Machado, Paulo Gabriel Barbosa de Carvalho and Márcia Farias Moreira, supervised by Professor Francisco Paulo Cerqueira Mota at UniFTC University center, Medical School, Salvador/BA.

 

Potential conflict of interest

No conflicts of interest potentially relevant to this article were reported.

 

Financing source

There was no external funding source for this study.

 

Authors' contribution

Conception and design of the research: Santos MA, Machado NRR, Carvalho PGB, Moreira MF; Data analysis and interpretation: Santos MA, Machado NRR, Carvalho PGB e Moreira MF; Writing of the manuscript: Santos MA, Machado NRR, Carvalho PGB e Moreira MF; Critical review of the manuscript for important intellectual content: Santos MA, Machado NRR, Carvalho PGB e Moreira MF.                                                                   

 

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