PCOS and Weight Loss: Why It Can Be Harder and What Helps

PCOS and Weight Loss: Why It Can Be Harder and What Helps

Many people with polycystic ovary syndrome describe weight loss as frustrating.

They may make changes that previously helped, only to find that:

• Progress is slow
• Appetite is difficult to manage
• Tiredness makes consistency harder

These experiences are real, but the explanation is more complicated than saying that PCOS automatically prevents weight loss.

The condition can affect:

• Hormones
• Insulin action
• Periods
• Mood
• Sleep
• Energy

Those effects can create additional barriers for some people.

At the same time, research has not identified one universal PCOS metabolism or one special diet that everyone with the condition must follow.

First, PCOS now has a new name

In May 2026, polycystic ovary syndrome was officially renamed polyendocrine metabolic ovarian syndrome, abbreviated to PMOS.

The NHS now uses PMOS and explains that the condition was previously called PCOS.

The new name reflects the fact that it can affect:

• Several hormone systems
• Metabolic health
• Ovarian function

It also avoids the misleading idea that everyone with the condition has ovarian cysts.

The diagnosis itself has not suddenly disappeared. People previously diagnosed with PCOS do not need to assume that their diagnosis is invalid.

This article uses PCOS in the title because it remains the term most people recognise and search for.

It uses PMOS throughout the main text in line with current NHS terminology.

The short answer

PMOS can make weight management feel harder for some people, but it does not make weight loss impossible.

Possible contributing factors include:

• Insulin resistance
• Tiredness and disrupted sleep
• Low mood or anxiety
• Irregular periods and changing symptoms
• Appetite or craving patterns
• Medicines that may affect weight
• Repeated restrictive dieting followed by regain
• Weight stigma and reduced access to appropriate support

The 2023 international evidence based guideline found that the exact mechanisms remain unclear.

It also states that structured lifestyle and weight management support appears to be as effective for people with PCOS as it is in the general population.

The useful message is not that someone needs to try harder. It is that the plan may need to be more individual, realistic and properly supported.

What is PMOS?

PMOS is a hormone condition that can affect anyone with ovaries.

Symptoms often begin around puberty and may change through adult life and after menopause.

Possible symptoms include:

• Irregular periods or long gaps between periods
• Unwanted facial or body hair
• Thinning hair on the scalp
• Acne or oily skin
• Difficulty becoming pregnant
• Weight gain or difficulty losing weight
• Tiredness
• Anxiety, depression or other effects on mental health
• Darkened, thickened skin around areas such as the neck or armpits

Not everyone has every symptom.

A person can have PMOS without living in a larger body, and an ultrasound appearance alone does not explain the full condition.

Does PMOS definitely make weight loss harder?

The evidence needs careful wording.

The Royal College of Obstetricians and Gynaecologists states that there is no strong evidence that PCOS by itself causes weight gain or makes weight loss difficult.

The international guideline similarly notes a lack of consistent evidence for specific physiological or behavioural differences related to weight when comparing people with and without the condition.

However, it also recognises that many affected people may have underlying mechanisms associated with:

• Greater weight gain over time
• More weight management challenges

Both points can be true:

• PMOS does not break the basic biology of weight change.
• Its symptoms and metabolic features can make the behaviours needed for weight management harder to sustain.

This is why simple advice such as “eat less and move more” often feels inadequate.

It describes part of the energy balance equation without addressing the person's symptoms, circumstances or barriers.

What role does insulin resistance play?

Insulin helps glucose move from the bloodstream into cells, where it can be used or stored.

Insulin resistance means the body needs more insulin to achieve the same effect.

Insulin resistance is an important feature of PMOS, although it is not present or expressed in exactly the same way in everyone.

It may be linked with:

• Higher insulin levels
• Changes in blood glucose control
• Increased risk of type 2 diabetes
• Changes in fat storage and distribution
• Greater metabolic risk when combined with higher weight

It is tempting to conclude that insulin resistance makes weight loss impossible.

That is not supported by the evidence.

People with insulin resistance can lose weight, although the wider hormonal and metabolic picture may affect how manageable the process feels.

The international guideline also cautions that routine insulin tests are of limited clinical value.

Diagnosis and management should not be based on a commercial “insulin resistance score” without proper medical interpretation.

Is a slow metabolism always the cause?

No.

There is no single metabolic rate shared by everyone with PMOS.

Energy needs vary with:

• Body size and body composition
• Age
• Movement and occupation
• Sleep
• Medicines
• Dieting history
• Other health conditions

Some people may have lower energy expenditure than expected.

However, plateaux and slow progress can also result from ordinary factors such as:

• Changing portion sizes
• Reduced activity during a diet
• Constipation
• Menstrual cycle related fluid changes
• An unrealistic estimate of energy needs

Do not assume that every difficulty is caused by PMOS.

An underactive thyroid, sleep apnoea, depression, medicines and other conditions can also affect weight, appetite and energy.

How can tiredness and sleep affect weight management?

The NHS lists tiredness as a possible PMOS symptom.

The international guideline also reports a higher prevalence of obstructive sleep apnoea in people with PCOS, independent of body mass index.

Poor sleep may affect:

• Appetite
• Food choices
• Energy for cooking
• Motivation to be active
• Recovery after exercise
• Mood
• Concentration

Someone who:

• Snores loudly
• Wakes choking or gasping
• Has witnessed pauses in breathing
• Experiences marked daytime sleepiness

should speak to a GP.

Treating a sleep problem may support overall health even if the scale does not change immediately.

See What Are the Warning Signs of Sleep Apnoea? for more information.

Does PMOS cause cravings or increased hunger?

Some people report strong hunger, cravings or difficulty feeling satisfied after meals.

These experiences may relate to several factors rather than one PMOS hormone.

Possible contributors include:

• Irregular meal patterns
• Highly restrictive dieting
• Poor sleep
• Stress
• Low mood
• Long gaps between meals
• Meals low in protein or fibre
• Medicines
• Individual appetite biology

A plan based on avoiding hunger entirely is unlikely to be realistic.

The aim is to make hunger more manageable and predictable through regular meals, filling foods and a level of energy reduction that can be sustained.

Is there a best PCOS or PMOS diet?

No single diet has been shown to be best.

The international evidence based guideline states that there is no evidence supporting one dietary composition over another for:

• Weight
• Metabolic outcomes
• Hormonal outcomes
• Reproductive outcomes
• Psychological outcomes

This means there is no requirement to follow:

• An extremely low carbohydrate diet
• A ketogenic diet
• Intermittent fasting
• A gluten free diet without a separate medical reason
• A dairy free diet without a separate medical reason
• A rigid “hormone balancing” meal plan
• An expensive supplement programme

Different approaches may suit different people.

The most useful pattern is one that:

• Supports overall nutrition
• Creates an appropriate energy deficit when weight loss is the goal
• Can be maintained in ordinary life

Do you need to cut out carbohydrates?

No. Carbohydrates are not automatically harmful in PMOS.

The type and portion can matter.

A balanced approach may include:

• Oats
• Potatoes
• Brown rice
• Wholegrain bread or pasta
• Fruit
• Beans, peas and lentils
• Vegetables

These foods can provide fibre, vitamins and minerals.

Combining carbohydrate with protein, vegetables and some unsaturated fat can create a more satisfying meal.

Someone may choose a lower carbohydrate approach if it suits their preferences and health needs, but extreme restriction is not required and can be difficult to sustain.

What should a practical eating pattern include?

A balanced meal might contain:

• A source of protein, such as eggs, fish, chicken, yoghurt, tofu, beans or lentils
• Vegetables or fruit
• A fibre rich carbohydrate, such as potatoes, oats, brown rice or wholegrain bread
• A small amount of unsaturated fat, such as olive oil, nuts, seeds or avocado

Practical habits include:

• Eating at reasonably regular times
• Choosing portions that match hunger and energy needs
• Including protein across the day
• Increasing fibre gradually
• Limiting drinks that provide substantial energy without much fullness
• Planning convenient meals for tired or busy days
• Allowing enjoyable foods without treating one meal as failure

Perfect eating is not required. Consistency across weeks matters more than one unusually good or difficult day.

How large should the calorie deficit be?

The international guideline supports an individual energy deficit when weight loss is the goal.

It should take account of:

• The person's energy requirements
• Weight
• Activity

A very large deficit may produce rapid early loss, but it can also increase:

• Hunger
• Tiredness
• Muscle loss
• The risk of abandoning the plan

For many people, gradual loss is more manageable.

The appropriate rate depends on starting weight, health, treatment and personal circumstances.

Do not respond to slow progress by repeatedly cutting food lower without checking whether the estimate, tracking method and time period are reliable.

Does exercise help with PMOS?

Yes.

Regular physical activity can improve general and metabolic health even when weight change is small.

The international guideline found no single type or intensity of exercise to be best for every PCOS outcome.

Sustainable activity based on the person's preferences and goals is recommended.

A balanced plan can include:

• Walking or cycling
• Swimming
• Dancing
• Home exercise
• Resistance training
• Active travel
• Sport
• Gradually reducing long periods of sitting

Strength training can help maintain or build muscle during weight loss.

Aerobic activity supports fitness and cardiovascular health.

Neither requires punishing sessions.

The current NHS PMOS page advises avoiding high intensity exercise if it worsens symptoms.

Choose an intensity that is safe, sustainable and compatible with your health.

Why is strength training useful?

During weight loss, the body can lose both fat and lean tissue.

Resistance training and adequate protein can help preserve muscle.

Muscle supports:

• Physical function
• Strength
• Long term weight maintenance
• Glucose use
• Confidence with everyday activity

Beginners can start with:

• Body weight movements
• Resistance bands
• Light weights

A physiotherapist or qualified exercise professional can adapt activity for pain, disability or another medical condition.

Does losing a small amount of weight help PMOS?

It can.

The RCOG explains that even a small amount of weight loss may improve symptoms and longer term health in people who are above their healthiest weight.

Possible improvements may include:

• More regular periods
• Better metabolic health
• Reduced risk of type 2 diabetes
• Improved fertility for some people
• Improvements in acne or unwanted hair over time
• Improved mood or confidence

These are possible benefits, not promises.

Weight loss does not cure PMOS and does not guarantee pregnancy, regular ovulation or improvement in every symptom.

Healthier eating, activity and sleep can provide benefits even when weight changes very little.

What if you are not overweight?

Weight loss should not be treated as a universal PMOS treatment.

If someone is not above their healthy weight, the focus should usually be on:

• A balanced diet
• Regular activity
• Maintaining weight
• Symptom management
• Metabolic checks
• Menstrual health
• Fertility goals where relevant
• Mental wellbeing

Trying to force weight loss in a person who does not need it can lead to:

• Undernutrition
• Loss of muscle
• Disordered eating

What medical checks may be useful?

PMOS affects more than body weight.

Depending on the person's symptoms and history, a clinician may consider:

• Blood pressure
• Blood glucose or an oral glucose tolerance test
• Cholesterol and other blood lipids
• Menstrual pattern
• Signs of excess androgen activity
• Mental health
• Symptoms of sleep apnoea
• Fertility goals
• Other possible causes of symptoms

The NHS says tests may include hormone blood tests, assessment of insulin resistance and an ultrasound in appropriate adults.

An ultrasound is not necessary or appropriate in every case, particularly in younger people.

Regular review matters because PMOS is associated with increased risks including:

• Type 2 diabetes
• High blood pressure
• Cardiovascular disease
• Fatty liver disease
• Womb cancer

Why do very infrequent periods need attention?

Long gaps between periods can allow the lining of the womb to remain thickened.

The RCOG advises that people having fewer than three periods a year may need treatment to protect the womb lining.

Options can include:

• A course of progestogen
• A contraceptive pill
• An intrauterine system

The appropriate option depends on pregnancy plans and clinical suitability.

Do not wait for weight loss to correct the problem. Speak to a GP if periods are absent or very infrequent.

Can metformin help with weight loss?

Metformin is primarily a medicine for type 2 diabetes, but it may be considered for some adults with PMOS, particularly for metabolic outcomes.

The international guideline recommends considering metformin in adults with PCOS and a BMI of 25 kg/m² or above for outcomes including:

• Insulin resistance
• Glucose
• Blood lipids

It may also be considered in some people below this BMI, although evidence is more limited.

Metformin is not a guaranteed weight loss medicine.

Lifestyle intervention and metformin may have similar effectiveness for some outcomes, and the decision should consider the person's:

• Symptoms
• Metabolic risk
• Preferences

Possible side effects include:

• Nausea
• Diarrhoea
• Abdominal discomfort

These are often related to dose.

Long term treatment may be associated with low vitamin B12 in some people, so monitoring may be appropriate.

Only take metformin when it has been prescribed for you. Do not buy it based on social media advice.

Can weight loss medicine be used with PMOS?

It may be considered for some adults who meet the normal clinical criteria for treatment.

The international guideline states that anti obesity medicines can be considered alongside active lifestyle support for higher weight in adults with PCOS, following the same principles used for the general population.

A PMOS diagnosis does not automatically make someone eligible.

A prescriber must assess:

• Body mass index and relevant health conditions
• Previous weight management attempts
• Current medicines
• Medical and family history
• Side effect risks
• Contraception
• Pregnancy plans
• Ability to attend monitoring and follow up

Treatment should be part of a wider plan, not a replacement for clinical review, nutrition or activity support.

Weight loss medicine, contraception and pregnancy

This is especially important because PMOS can affect ovulation and periods.

Irregular periods do not mean pregnancy is impossible.

The MHRA states that GLP 1 medicines should not be taken:

• During pregnancy
• While trying to become pregnant
• While breastfeeding

Effective contraception is recommended when pregnancy is possible.

Current MHRA guidance says:

• Semaglutide should be stopped at least two months before trying to become pregnant
• Tirzepatide should be stopped at least one month before trying to become pregnant
• People using tirzepatide with an oral contraceptive should add a barrier method for four weeks after starting and for four weeks after each dose increase, or discuss switching to a non oral method

Speak to the prescriber promptly if pregnancy is suspected.

Do not make assumptions based on an irregular cycle.

What about inositol and other supplements?

Inositol is widely promoted for PCOS, but the evidence is more limited than online marketing often suggests.

The international guideline says inositol may be considered according to individual preferences, but clinical benefits for:

• Weight
• Ovulation
• Unwanted hair

are limited.

It does not recommend a specific type, dose or combination because the evidence is insufficient.

Supplements can:

• Vary in quality
• Interact with medicines
• Create unnecessary cost

Tell the clinician about every supplement being used.

Do not rely on a supplement in place of assessment for irregular periods, fertility concerns or metabolic risk.

How should progress be measured?

The scale is one measure, but not the only one.

Useful measures can include:

• Weight trend across several weeks
• Waist measurement where appropriate
• Strength and fitness
• Blood pressure
• Blood glucose and cholesterol results
• Menstrual pattern
• Energy and sleep
• Ability to maintain the plan
• Changes in symptoms important to the individual

Daily weight can move because of:

• Fluid
• Bowel contents
• Salt
• Carbohydrate intake
• The menstrual cycle

Compare trends under similar conditions rather than reacting to one reading.

A practical starting plan

Week one: understand the current pattern

For several ordinary days, note:

• Meals
• Snacks
• Drinks
• Activity
• Sleep
• Hunger

The aim is to identify patterns, not to judge them.

Week two: improve meal structure

Choose one or two repeatable changes, such as:

• Adding protein at breakfast
• Planning lunch
• Including vegetables with the evening meal

Week three: build movement

Add activity that is realistic.

This might be:

• A daily walk
• Two short resistance sessions
• Breaking up long periods of sitting

Week four: review the trend

Look at:

• Weight
• Waist
• Hunger
• Energy
• Sleep
• Adherence

If the plan is not producing the intended result, adjust one part rather than starting a completely different diet.

Clinical support can be added at any stage, particularly where symptoms, metabolic risk or previous unsuccessful attempts make self management difficult.

How Keltoi approaches weight management

Keltoi provides a doctor led online weight management pathway for eligible adults in the UK.

The website gathers information to give the clinician a structured overview of the person's health and weight history.

This can include:

• Medical conditions such as PMOS
• Current medicines
• Previous treatment
• Measurements
• Symptoms
• Treatment preferences

All clinical decisions remain with Dr Waqar Ahmed.

Completing the online process or selecting a preferred programme does not guarantee that a particular treatment will be prescribed.

The clinician may:

• Request more information
• Recommend lifestyle support
• Consider a licensed treatment where clinically appropriate
• Suggest GP investigation or monitoring
• Choose another treatment
• Decide that treatment is not suitable

PMOS is relevant to the assessment, but it does not replace the usual safety and eligibility checks.

When should you speak to a GP?

Arrange an appointment if:

• You think you may have PMOS
• Periods are very irregular or absent
• Unwanted hair growth, acne or hair loss is worsening
• Symptoms affect everyday life, work or relationships
• You are struggling to become pregnant
• Weight changes rapidly without a clear reason
• Tiredness is persistent
• There are symptoms of diabetes
• Snoring, breathing pauses or daytime sleepiness suggest sleep apnoea
• Anxiety, depression or eating concerns are affecting wellbeing

Seek urgent help for severe symptoms or a mental health crisis.

Weight loss advice is not a substitute for assessment of a new or worsening medical problem.

Frequently asked questions

Is PCOS now called PMOS?

Yes.

In May 2026, polycystic ovary syndrome was renamed polyendocrine metabolic ovarian syndrome.

The NHS now uses PMOS and explains that it was previously called PCOS.

Both terms are likely to appear during the transition.

Can you lose weight with PMOS?

Yes.

PMOS does not make weight loss impossible.

The international guideline states that structured lifestyle and weight management support appears to be as effective in PCOS as in the general population.

Why am I gaining weight with PMOS?

There may not be one cause.

Possible contributors include:

• Insulin resistance
• Sleep
• Mood
• Appetite
• Medicines
• Activity
• Dietary patterns

Rapid or unexplained gain should be assessed rather than automatically blamed on PMOS.

What is the best diet for PCOS weight loss?

No single diet has been shown to be best.

A sustainable balanced eating pattern that creates an appropriate energy deficit is more important than following a named PCOS diet.

Do I need to avoid carbohydrates?

No.

Choose portions and sources that suit your needs.

Wholegrains, potatoes, oats, fruit, vegetables and pulses can all form part of a balanced diet.

Does losing weight cure PMOS?

No.

Weight loss may improve some symptoms and metabolic risks in people carrying excess weight, but it does not cure the condition or guarantee improvement in every symptom.

Is metformin a weight loss treatment for PMOS?

Metformin may be considered for metabolic outcomes in some people with PMOS, but it is not a guaranteed weight loss medicine.

It should only be used following an individual clinical assessment.

Can I use weight loss injections if I have PMOS?

Possibly, if a prescriber decides that you meet the usual eligibility and safety criteria.

PMOS alone does not guarantee treatment.

Pregnancy plans and contraception require particular attention.

Can weight loss improve fertility?

It may improve ovulation and fertility for some people above their healthiest weight, but it is not a guarantee of pregnancy.

Fertility concerns deserve proper assessment and should not be reduced to weight alone.

What if I have PMOS but do not need to lose weight?

Focus on:

• Balanced nutrition
• Regular activity
• Symptom management
• Metabolic checks
• Reproductive health

Weight loss is not required for everyone with the condition.

What to remember

PCOS is now called PMOS, reflecting its wider hormonal, metabolic and ovarian effects.

Weight loss can feel harder for some people because factors such as:

• Insulin resistance
• Tiredness
• Sleep
• Mood
• Appetite
• Previous dieting experiences

may all affect consistency.

The evidence does not support the idea that weight loss is impossible or that one special PMOS diet works best.

Sustainable eating, regular activity, strength training, adequate sleep and behavioural support can help.

Medical treatment may be appropriate for some people, but it requires an individual assessment and careful discussion of pregnancy and contraception.

Most importantly, care should address the whole condition. Periods, metabolic health, sleep, fertility and mental wellbeing matter whether or not the number on the scale changes.

Sources

• NHS: Polyendocrine metabolic ovarian syndrome
• NICE: Polyendocrine metabolic ovarian syndrome guideline in development
• RCOG: PCOS and long term health
• RCOG: International evidence based guideline on PCOS
• International evidence based guideline for the assessment and management of PCOS 2023
• Monash University: PMOS guideline and resources
• GOV.UK: GLP 1 medicines for weight loss and diabetes

Last updated: 21 August 2026

Medical disclaimer: This article provides general information and is not a diagnosis, personal treatment plan or guarantee of weight loss or fertility. Speak to a GP or appropriately qualified clinician about symptoms, medicines, contraception and pregnancy plans. Do not start, stop or change prescribed treatment without clinical advice.