A major health issue on a global scale is obesity. According to the WHO (World Health Organisation), obesity is characterised as an abnormal or excessive fat buildup that poses health problems. Obesity is a complex condition that causes various other health complications. 

The mortality caused by obesity is on the rise. Obesity is a preventable and reversible condition. Genetic factors, culture, unhealthy eating habits, and environmental factors are the causes of obesity. 

Several other causes include reduced physical activity, disturbed sleep, endocrine disorders, and drugs. Obesity and infertility are interlinked but the exact mechanism of how obesity affects fertility is complex.

Diagnosis of obesity 

Body Mass Index (BMI), a simple approach to quantify obesity is used, though not always reliable. BMI categories obesity as >30 kg/m2 depending upon ethnic group. 

Obesity is diagnosed by assessing skin fold thickness, dual energy radiographic absorptiometry (DEXA), and body composition analysis (BCA). 

Causes of obesity

  • Energy imbalance – When the calorie consumption is higher than the energy used over an extended period, obesity is the primary effect. The body stores this additional energy as fat. 

  • Genetics – Some people can be more prone genetically to gain weight more easily. 

  • Hormonal regulations – In controlling hunger, metabolism and fat storage, hormones including insulin, leptin, and ghrelin are essential. Increased food consumption and fat storage may result from hormonal dysregulation. 

  • Adipose tissue – It is an endocrine organ, It not only stores fat but also secretes hormones and cytokines. In obese individuals, the tissues can be inflamed by releasing inflammatory mediators that increase the risk of metabolic dysfunction and insulin resistance. 

  • Insulin resistance – It is a condition where the cells do not respond well to insulin. This leads to increased insulin levels and fat storage. 

  • Neurotransmitter – The control of hunger and satiety is largely dependent on the brain. Food cravings and reward systems are influenced by several neurotransmitters. Overeating can result from obesity’s disruption of various signalling networks. 

  • Gut microbiota – Inflammation, food absorption, and energy metabolism may all be impacted by imbalances in the gut flora. Recent studies point to a connection between the composition of the gut microbiota and obesity.

  • Behavioural factors – Stress, emotional problems, and mental health issues can contribute to overeating or bad eating habits. 

  • Socio-economic factors – Access to wholesome food and opportunities for exercise might be influenced by socioeconomic position. 

  • Environmental factors – Access to high-calorie, processed foods, sedentary lifestyles, and cultural influence can contribute. 

Obesity and its effect on the reproductive system 

Both males and females can experience distinct implications of obesity on the reproductive system.

Infertility in females

  • Obesity in females is frequently linked to anovulation (lack of ovulation) and irregular menstrual cycles. This may result in infertility or conceiving problems. 

  • Obesity causes many other health complications. The most common condition associated with obesity in females is polycystic ovary syndrome (PCOS). PCOS is an endocrine disorder where there is a hormonal imbalance in the body. It is not known what causes PCOS specifically.

  • It is usually identified by irregular periods, polycystic ovaries, and hyperandrogenism. About 8-13% of women of reproductive age are affected by PCOS. Women often experience irregular periods. 

  • PCOS can prevent ovulation, which is the process by which an egg is released from the ovary. Women who have PCOS may develop little sacs packed with fluid on their ovaries. Although these cysts are typically unharmful, they can make it challenging for an egg to release.

  • Infertility is the inability to conceive a child. It is caused in both males and females. A study reveals that 8-12 % of couples face infertility worldwide, though this varies from country to country (WHO, 2023) .

  • The oocyte’s qualitative and quantitative development, fertilisation, embryo development, and implantation are all compromised.

  • Obesity can cause hormonal imbalances that interfere with reproductive processes by upsetting the ratio of sex hormones like oestrogen and testosterone. 

  • Insulin resistance is a common complication of obesity, which can impair the ovaries’ capacity to release eggs and cause ovulatory problems in females.

  • Obese women who do get pregnant are more likely to experience pregnancy complications such as gestational diabetes, preeclampsia, and C-sections. 

  • Obesity can increase the dangers of reproductive treatments like in-vitro fertilisation (IVF) and reduce their effectiveness. 

  • It can cause depression, low self-esteem, and psychological stress, all of which can hurt a person’s desire and capacity to conceive. 

How infertility is caused in men?

Fertility issues can be caused by a wide range of illnesses and other factors. The cause is not always known. Infertility cases caused by problems with male reproduction account for one-third of all instances. 

The abnormalities that influence how the testicles function are the most frequent causes of infertility in males. Hormone imbalances or obstructions in the male reproductive system are additional problems. 

Approximately 10%-15% of infertile males have no sperm. Lack of sperm can be brought on by hormonal imbalance or sperm movement obstruction. Men might produce fewer sperm than usual when they are infertile. Varicocele, an enlarged vein in the testis, is the most frequent cause of this disorder. 

Signs and symptoms of male infertility 

  • Decreased sexual desire, difficulties sustaining an erection, or difficulty ejaculating or ejaculating little amounts of fluids. 
  • Having discomfort or a lump in the testicle area.
  • Inability to smell
  • Respiratory infections
  • Abnormal breast development
  • Less hair on the face, body, or other chromosomal or hormonal anomalies.
  • Reduced sperm count. 

How to manage infertility?

A combination of medical, lifestyle, and emotional therapies are frequently used to manage infertility. Consider these actions when regulating infertility

  • It is advised to consult a reproductive endocrinologist or a fertility specialist. 

  • Hormone testing, ultrasound imaging, male semen analysis, tests to determine ovulation, and examinations to evaluate the health of the reproductive organs.

  • Change your lifestyle to a healthier one to increase the chances of conception. This entails keeping a healthy weight, eating a balanced diet, exercising frequently, managing stress, and quitting smoking, binge drinking, and using drugs. 

  • Doctors might recommend fertility drugs depending on the underlying cause of infertility. These can help men produce higher-quality sperm or can help women with ovulatory problems.

  • Surgery could be required to address anatomical problems that are causing infertility, such as fibroids or obstructed fallopian tubes. 

  • Assisted reproductive technologies (ART) can be considered as an option. ART like Intrauterine insemination or in vitro fertilisation. These techniques can assist overcome some obstacles to fertility and raise the likelihood of pregnancy.

  • Experiencing infertility can be stressful. To manage the stress and emotions associated with fertility therapy, think about getting counselling or joining a support group. 

  • Medication or surgery can help manage underlying medical disorders including polycystic ovarian syndrome (PCOS) or endometriosis which may increase fertility. 

  • In cases of severe male factor infertility or certain female infertility issues, one can consider a sperm donor, egg donor, or gestational surrogacy. 

  • Keep educating individuals about fertility or specific conditions. 

  • Recognise that success with fertility treatments is not assured and that they may take time. Managing expectations and keeping a good mindset are critical.  

To conclude obesity is a global health concern characterised by excessive fat accumulation leading to various health complications. It is a preventable and reversible condition, it is complex and involves genetic, cultural, environmental, behavioural, and socioeconomic factors. Understanding its causes, such as energy imbalance, genetic predisposition, hormonal regulation, and behavioural factors, is crucial. 

Obesity affects both females and males, contributing to infertility in females due to anovulation, irregular menstrual cycles, and conditions like polycystic ovary syndrome (PCOS). In males, infertility can result from testicular abnormalities, hormone imbalances, or sperm movement obstructions. A holistic approach addressing physical, emotional, and lifestyle aspects is essential for improving conception chances and navigating reproductive health complexities. 


Kripa N,
Senior Clinical Dietitian, Simplyweight