Dietary interventions in overweight or obese men and women should consider the degree of obesity, dietary preferences, and food availability.

If an eating disorder is suspected, referrals to the dietitian and clinical psychologist should be considered.

Strategies such as face-to-face education sessions and practical advice on approaches to healthy eating tailored to the patient should be incorporated.

It is currently recommended that women with BMI >25 should aim for weight loss via caloric restriction through balanced dietary approaches irrespective of diet composition.

In the general adult population, a target energy deficit of 2500 kJ daily is recommended for weight loss.

An individualised approach works best.

The aim should be to lose weight at a safe and sustainable rate of 0.5–1 kg a week, and for most women, the initial advice should be to reduce their energy intake by 600 cal a day.

To consider swapping unhealthy and high-energy food choices (fast food, processed food, sugary drinks, and alcohol) for healthier choices.

Very low-calorie diet which involves consumption of less than 800 cal a day, can lead to rapid weight loss, but may not be suitable for everyone. Such diets should not be followed for longer than 12 weeks at a time. They should only be recommended under the supervision of a suitably qualified healthcare professional.

Evidence shows that exercise benefits overweight women even in the absence of significant weight loss.

Thrice-weekly moderate exercise for at least 30 minutes has been demonstrated to reduce BMI, waist circumference, and insulin resistance (IR) in young PCOS women.

A recent meta-analysis found that weight-loss interventions, particularly diet and exercise, improved pregnancy rates and ovulatory status.

Miscarriage rates remained unchanged by weight-loss interventions.

The meta-analyses also showed that weight loss had a nonsignificant advantage over weight loss medications such as metformin with respect to achievement of pregnancy or improvement of ovulation rates.

Pharmacological agents are mainly indicated when patients fail to lose significant weight despite lifestyle changes and a low-calorie diet.

These agents have been shown to induce modest weight loss but are not suitable for long-term weight maintenance.

These have mainly included metformin (an insulin sensitiser), orlistat (a lipase inhibitor), sibutramine (a selective serotonin and norepinephrine reuptake inhibitor), and liraglutide [a glucagon-like peptide-1 (GLP-1) receptor agonist].

When prescribing the appropriate weight-losing drug, it is paramount to consider the safety of these drugs should a woman conceive while taking them.

The safety of acarbose in pregnancy is not established.

The use of weight-loss medications is contraindicated during pregnancy.

Out of all the drugs mentioned previously, pharmacokinetics of the orlistat places it in a favourable position due to its low absorption and first-pass metabolism resulting in a bioavailability of less than 1%.

Lifestyle interventions should still be considered the first-line therapy, with drug use largely reserved for monitored trials.

Metformin is a synthetically derived biguanide that decreases hepatic glucose production and intestinal absorption of glucose, while increasing the peripheral uptake and utilisation of glucose.

It also stimulates fat oxidation and reduces fat synthesis and storage. Metformin decreases IR and enhances insulin sensitivity at the cellular level.

Metformin appears to promote weight loss and offers protection from the macrovascular complications of diabetes.

Metformin is administered orally in doses of 1500–2000 mg in divided daily doses.

The most common side effects of metformin are gastrointestinal in nature such as nausea, vomiting, and diarrhoea. Such side effects decrease with time and can be lessened by dose reduction and taking the metformin with food.

The most serious side effect, lactic acidosis, is rarely seen.

No obstetric complications or congenital anomalies were described.

It is also recommended periconceptionally to reduce the risk of ovarian hyperstimulation syndrome (OHSS) with IVF.

It has been observed that nonobese women with PCOS respond better to metformin than obese women.

A Cochrane review in 2017 showed that combined therapy with metformin and clomiphene citrate has improved ovulation rate and clinical pregnancy than using clomiphene citrate alone in obese women with PCOS.

Metformin is mainly used in women with PCOS as a second-line option for ovulation induction (either for clomiphene resistance or combined with clomiphene), especially in those with a BMI of 35 and over.

Metformin is also used along with weight management strategies as a first-line agent in women with high BMI and wishing to pursue fertility treatment in near future.

Sibutramine blocks the reuptake of the neurotransmitters dopamine, norepinephrine, and serotonin. Sibutramine is no longer recommended in clinical practice because of the risk of serious cardiovascular problems in some patients who take it. Sibutramine has been withdrawn in Europe and the United States but is still available on the Internet.

Orlistat inhibits pancreatic lipase, resulting in a 30% reduction in the absorption of ingested fat leading to weight loss.

Orlistat is recommended once the woman has made a significant effort to lose weight through diet, exercise, and lifestyle changes. It is recommended that the diet should be rich in fruit and vegetables. It is used in conjunction with a balanced low fat diet for the treatment of obese women with a BMI ≥30 kg/m ² or overweight patients (BMI ≥28 kg/m ² ) with associated risk factors.

If a meal is missed or contains no fat, the dose of orlistat should be omitted.

A single orlistat capsule (120 mg) should be taken with water immediately before, during, or up to 1 hour after each main meal (up to a maximum of three capsules a day).

Treatment should continue beyond 3 months if there is loss of 5% of body weight. If weight loss is demonstrated, orlistat should be continued for 12 months or more.

Women with type 2 diabetes may take longer to lose weight using orlistat, so the target weight loss after 3 months should, therefore, be slightly lower.

The gastrointestinal effects of orlistat result in an increase in faecal fat as early as 24–48 hours after dosing. Upon discontinuation of therapy, faecal fat content usually returns to pretreatment levels within 48 72 hours.

Common side effects of orlistat include steatorrhoea, diarrhoea, flatulence, abdominal discomfort, headaches, and upper respiratory tract infections.

Women taking the combined oral contraceptive pills should use an additional method of contraception if they experience severe diarrhoea while taking orlistat.

The effect of orlistat in patients with hepatic and/or renal impairment, children, and elderly patients has not been studied.

Contraindications to the use of orlistat include hypersensitivity to the active drug substance or to any of the excipients, chronic malabsorption syndrome, and cholestasis.

The study shows no risk of birth defects from orlistat use. Orlistat is not recommended for pregnant or breastfeeding women.

Orlistat appears to be equally effective with metformin in reducing weight, IR, and testosterone levels.

Liraglutide (GLP-1 receptor agonist) stimulates insulin secretion and lowers inappropriately high glucagon secretion in a glucose dependent manner.

Liraglutide reduces body weight and body fat mass through mechanisms involving reduced hunger and lowered energy intake as GLP-1 is a physiological regulator of appetite and food intake.

Liraglutide has been utilised in the management of patients with BMI >30 kg/m ² or BMI 27–30 kg/m ² and obesity-related comorbidities.

To improve the gastrointestinal tolerability, the recommended starting dose is 0.6 mg daily. After at least 1 week the dose should be increased to 1.2 mg. Some patients are expected to benefit from an increase in dose from 1.2 to 1.8 mg and based on clinical response; after at least 1 week, the dose can be increased to 1.8 mg.

Common side effects of liraglutide include nausea, vomiting, stomach upset, decreased appetite, diarrhoea, and constipation.

Liraglutide should not be used during pregnancy.

A recent double-blind trial by Wilding et al. showed 2.4 mg of semaglutide once weekly (another GLP-1 receptor agonist) plus lifestyle intervention was associated with sustained, clinically relevant reduction in body weight.

This is a nutritional supplement which contains folic acid and myo-inositol. This has an antioxidant role and increases insulin sensitivity in obese women with PCOS and helps in weight loss. Taken during treatment it has been shown to improve egg and embryo quality and reduce the risk of OHSS. Evidence is accumulating that myo-inositol is efficient enough to change sperm parameters to increase the chance of fertility. It can be taken throughout pregnancy and reduces the incidence of gestational diabetes.

Bariatric surgery represents the most successful treatment that results in sustained long-term weight loss.

The percentage of body weight loss at 2 years after bariatric surgery can approach 60%.

Indications for this procedure are well established by the American Bariatric Society and suggest that candidates should have at least a BMI >40 without serious comorbidities (e.g., diabetes, hypertension) or at least a BMI >35 in the presence of one serious comorbidity.

Candidates with BMI <35 are considered if they have uncontrolled type 2 diabetes or metabolic syndrome.

Absolute contraindications include serious depression or psychosis, eating disorder, alcohol abuse, heart disease, and coagulopathy.

It is estimated that only 1% of the population that meets the criteria for these procedures undergoes surgery.

Patients should be carefully screened to optimise the success of a considered procedure.

Psychological assessment and appropriate setting of expectations before surgery is essential.

Sustainable weight loss after a bariatric procedure requires significant lifestyle changes.

Preoperative assessments include reviewing a patient’s previous attempts at weight loss, eating and dietary styles, physical activity, and history of substance abuse.

A review of the patients’ medical comorbidities and consequent suitability for anaesthesia are the key determinants of candidacy for surgery.

Bariatric procedures are characterised as restrictive, malabsorptive, or a combination of the two.

Restrictive surgeries such as the sleeve gastrectomy aim to create a smaller gastric pouch that reaches capacity soon after food consumption to induce satiety.

The sleeve gastrectomy is a partial gastrectomy in which most of the greater curvature of the stomach is removed, thus producing a more “tubular” stomach.

Sleeve gastrectomy has been described as a less complex procedure than bypass and is associated with shorter operating time, a lower rate of blood loss, and a lower rate of reoperation among other morbidities.

Evidence has accumulated supporting sleeve gastrectomy as the most performed bariatric procedure in the United States since 2013.

Roux-en-Y gastric bypass is the second most practiced type of bariatric surgery.

This procedure is characterised by the creation of a small gastric pouch divided from the distal stomach and anastomosed to a “Roux” limb of small bowel. The proximal small intestine is then divided, and a limb is created that drains secretions from the gastric remnant, liver, and pancreas. The net effect is to have two stomach chambers that anastomose to the small intestine at different points. The stomach remnant drains proximally, and the newly created smaller functional stomach drains distally through the Roux limb. The decreased size of the stomach acts to restrict caloric intake, and the bypass of a segment of small bowel has a malabsorptive effect.

Roux-en-Y gastric bypass limit energy intake by effectively shortening the length of the gastrointestinal tract.

Malabsorptive procedures and consequent nutritional deficiencies are thought to drive the increase in intrauterine growth restriction and small for gestational age (SGA) infants seen in initial observational studies of pregnancy in bariatric surgery patients.

Bypass, with its impact on absorption, can produce a higher degree of weight loss over a shorter time frame.

The expected 2-year weight loss after a Roux-en-Y procedure is about 70% compared to 60% for sleeve gastrectomy.

Other bariatric procedures which may be considered include the much less commonly performed biliopancreatic diversion with duodenal switch, the intragastric balloon, and vagal blockade.

The biliopancreatic diversion involves manipulation of the pylorus, duodenum, and ileum and is considered a technically difficult operation with a significant complication rate.

Intragastric balloon has promise as a bridge to another procedure and has been approved for patients at a lower BMI threshold than traditional bariatric surgery (BMI 30–34.9).

It involves the placement of a soft saline-filled balloon into the stomach that promotes the sensation of satiety and gradually degrades after about 6 months.

Vagal blockade involves the placement of an electric pulse generator that is designed to lead to the decreased sensation of hunger.

Initial data on the effects of weight-loss surgery on fertility have been encouraging, however limited.

Various studies support the conclusion that surgical treatment of obesity tends to reverse the altered reproductive hormone profile seen in this population.

Further, bariatric surgery has been associated with profound changes extending to the hypothalamic pituitary adrenal axis.

American Congress of Obstetricians and Gynecologists (ACOG) have highlighted the potential for bariatric surgery to improve fertility outcomes through restoration of ovulation and reversing pathologic changes in PCOS and spontaneous conception, however it should “not be considered a treatment for infertility.”

The American Society for Reproductive Medicine suggests that bariatric surgery appears safe in a population looking forward to becoming pregnant and has potential to lead to improvement in markers of reproductive health.

Some studies have suggested a negative impact on fertility in some patients.

Nutritional deficiencies after malabsorptive procedures have been proposed as a potential mechanism for subfertility.

Bariatric surgery is noted to cause a significant decrease in AMH levels in women under 35.

Importantly, this effect was not seen in those above 35. This change has been attributed to stress involved with operation and decreased absorption of precursors relevant in AMH production.

ACOG recommend delaying pregnancy for 12–24 months.

Post bariatric surgery patients who became pregnant within 2 years had higher rates of prematurity, neonatal intensive care unit admission, and SGA infants.

Systematic review of studies indicates IVF of women with BMI >25 has a 10% lower success rate than those with less than this figure.

If a woman develops OHSS, a complication of IVF, this can in turn increase the risk of known bariatric surgery complications, such as intestinal obstruction and internal hernia.

Another issue of concern is adherence to the recommended postprocedural delay before conception.

Obese men achieving weight loss through medical and surgical means have been shown to increase quality of life, decrease rates of erectile dysfunction, and possibly improve derangements in reproductive hormone profile.

There is no specific data that has been able to characterise improvements in a couple’s fertile potential through surgical weight loss in the male.

In those couples that require assisted conception treatment, it could be argued that ICSI should be offered when there is male obesity, to overcome the negative effects demonstrated on sperm function.

Overweight subfertile men and women appear most deterred from exercise by the perception that it causes tiredness and is hard work. Such perceptions seem to decrease with continuation of an exercise program.

Effective weight management programs should include behavioural changes to increase the person’s physical activity level. These could include setting goals, stimulus control, and relapse prevention.

A multidisciplinary, holistic approach to weight loss, including primary care physician, gynaecologist, endocrinologist, exercise physiologist, dietitian, and psychologist is recommended in women with PCOS who have established metabolic complications.