Plans for Your Body · Blood sugar & insulin · Hormones, sleep & ageing
The PCOS plan
PCOS is a hormone problem with an insulin engine.
The goal: Most women with PCOS are insulin resistant, lean ones included, and high insulin pushes the ovaries to make more testosterone. Lower the insulin: cut sugar and refined carbs, eat in a window, lift and walk, sleep. Losing 5–10% of your weight, if you carry extra, often brings cycles back. Your doctor handles the rest.
The usual PCOS appointment ends with a birth control pill for the cycles, something for the skin, and “lose weight” for everything else. The pill can be the right call. It just doesn’t touch what drives the syndrome in most women: too much insulin. This plan measures it, lowers it, and works alongside whatever your doctor prescribes.
- MeasureFasting insulin · glucose tolerance · lipids · waist · cycle log
- ChangeCut refined carbs · eating window · strength and cardio · sleep
- RetestInsulin and cycles at 3–6 months, with your doctor
Treat the symptoms if you need to. Treat the engine as well.
Not medical advice
Discuss everything here with a medical doctor before acting on it — supplements included. Your doctor has your bloodwork and history. We have neither.
02 Why it matters
It’s not just about your ovaries.
How common
PCOS affects roughly one woman in ten of reproductive age, and many don’t know they have it. Irregular cycles, acne, unwanted hair, thinning scalp hair and trouble conceiving are the visible parts.
What it leads to
Higher risk of type 2 diabetes, gestational diabetes, fatty liver, high cholesterol, sleep apnea, depression and anxiety. Very infrequent periods raise the risk of endometrial cancer. The international guideline treats PCOS as a lifelong metabolic condition, not just a fertility one.
The evidence
The 2023 guideline says losing 5–10% of body weight, if you carry extra, gives clinically meaningful improvements in cycles, hormones and metabolism. Insulin-lowering is why.
Fix the insulin and several of these move together.
03 How it works
High insulin tells the ovaries to make testosterone.
In PCOS, the ovaries respond to insulin by making more androgens, the “male” hormones. High insulin also makes the liver produce less SHBG, the protein that binds testosterone, so more of it is free to act. More androgen means irregular ovulation, acne and hair growth. Women with PCOS are often insulin resistant regardless of weight, so the pancreas keeps insulin high, and the cycle continues.
- Diagnosis
- In adults, two of three: irregular or absent ovulation, high androgens (on blood tests or signs like acne and hair growth), and polycystic ovaries on ultrasound or a high AMH blood test. Other causes ruled out first.
- Insulin resistance
- Present in most women with PCOS, including many lean ones, and worse with weight. It’s the most changeable part of the syndrome.
- SHBG
- Sex hormone-binding globulin. Low when insulin is high. A rising SHBG is a sign your insulin is coming down.
- Irregular cycles
- Shorter than 21 days, longer than 35, or fewer than eight a year. Each one that goes missing is a cycle without ovulation.
- Muscle
- The biggest glucose sink in the body. More muscle means less insulin needed, which means less signal to the ovaries.
04 The steps
Measure. Lower insulin. Track your cycles.
Measure · Week 0
Find out how much of your PCOS is insulin.
- Fasting insulin and glucosemorning, after an overnight fast
Together they give HOMA-IR, a simple insulin-resistance score. Fasting insulin often isn’t covered in Canada. It’s cheap to pay for. With PCOS, it shows how much of the syndrome is being driven by insulin, and gives you a number to bring down.
- Glucose tolerance testask your doctor
The 2023 guideline calls the 75 g oral glucose tolerance test the most accurate way to check blood sugar in PCOS, and recommends checking every 1–3 years. HbA1c and fasting glucose can miss it.
- Lipids and waistTG/HDL, waist-to-height
High triglycerides, low HDL and a waist over half your height all point to insulin resistance.
- Testosterone and SHBGwith your doctor
Your starting point for the hormone side. If you’re on the pill, it changes these results; ask your doctor how to read them.
- Cycle logan app or a calendar
Date every period. Cycle length is the cheapest outcome measure you have.
Change the inputs · Months 1–6
Less insulin, more muscle.
- Sugar and refined carbscut hard
Sugar, sweet drinks, juice, white flour and most packaged snacks. The fastest lever on insulin, blood sugar and triglycerides. Fewer glucose spikes, less insulin, less signal to the ovaries to make androgens.
- Real foodprotein first
Build meals on protein, vegetables and natural fats: fish, meat, eggs, dairy, legumes, nuts. Protein and fibre keep you full and flatten glucose spikes. Protein at every meal also helps with the appetite swings many women with PCOS describe.
- Eating windowdaily, e.g. noon to 8 pm
Eat inside a fixed window and not outside it. Fewer insulin spikes per day, fewer chances to overeat. In a small Chinese trial, an eight-hour window for five weeks improved insulin, testosterone and menstrual regularity in women with PCOS.
- Trainingstrength 2+ days/week, cardio 150–300 min/week
Lift, and walk briskly or cycle most days. Muscle is where most of a meal’s glucose ends up, so more muscle means more room for it. Cardio makes that muscle more sensitive to insulin. This matches the PCOS guideline. Lifting matters more than people think: muscle is where the glucose goes.
- Sleep7+ hours
One short night measurably worsens insulin sensitivity, blood sugar and appetite the next day. The cheapest part of the protocol, and the most skipped. Sleep apnea is more common with PCOS. Snoring, gasping or daytime sleepiness are worth raising with your doctor.
- Alcoholnone while fixing the numbers
It goes straight to the liver, raises triglycerides and adds to liver fat. Less is better; none is best while you’re fixing the numbers.
Fasting with PCOS
Don’t do extended fasts if you’re pregnant, trying to conceive, breastfeeding, underweight, or have a history of disordered eating, which is more common with PCOS. An eating window is a gentler start. Talk to your doctor first.
Longer fasts · optional, with your doctor’s OK
For when the window isn’t enough.
- 36-hour fastonce a week
Dinner one day, then only water, black coffee or tea until breakfast two days later. A standard protocol in Dr. Fung’s clinic: long enough for insulin to fall and the body to draw on stored fat. A pinch of salt helps with headaches. Only if you’re not pregnant or trying to conceive, and the eating window is already easy.
- Inositolevidence still thin
Myo-inositol is popular for PCOS and has fewer stomach side effects than metformin. The review behind the 2023 guideline found the evidence limited and inconclusive. If you try it, tell your doctor and judge it by your cycles and your numbers.
Retest · Months 3–6
Cycles and insulin. Both should move.
- Fasting insulin, lipids, SHBGsame lab
Compare with week 0. Falling insulin and rising SHBG mean the engine is slowing.
- Cycle logthe real outcome
Shorter, more regular cycles are ovulation returning. Many women see it within a few months.
- Weight and waistif you carry extra
5–10% down within six months is the guideline’s idea of success. Waist is the better measure for lean PCOS.
- If the numbers won’t moveyour doctor
Take the before-and-after numbers to your doctor. Whether you need medication is their call. Needing it isn’t failure. Ask your doctor about metformin, the pill, or other treatments for symptoms that don’t shift. For fertility, ask about letrozole and referral: in Legro’s large NIH trial, letrozole led to more live births than the older drug clomiphene, 27.5% against 19.1%. This plan works alongside them.
05 The rules
Short list. No exceptions.
Choose
- Protein and vegetables at every meal
- A fixed eating window
- Strength training at least twice a week, cardio most days
- 7+ hours of sleep
Avoid
- Sugar, sweet drinks, juice and white flour
- Crash diets and extreme restriction. They backfire, and PCOS raises the risk of disordered eating
- Supplement stacks sold as a “PCOS cure”
- Assuming lean means insulin is fine
Non-negotiables
- Get your blood sugar checked properly, ideally with a glucose tolerance test.
- Talk to a medical doctor before you fast or start a supplement, and stop fasting if you’re trying to conceive.
- See your doctor if you go more than three months without a period.
- Track your cycles. They’re your best progress report.
06 Checkpoints
What to track, and what good looks like.
Your doctor sets your targets. These are the standard thresholds.
| What | Target | How and when |
|---|---|---|
| Cycle length | 21–35 days, 8+ cycles a year | Log every period. |
| HOMA-IR | Under ~1.0 is ideal; over ~2 to 2.5 suggests insulin resistance | Fasting glucose (mmol/L) × fasting insulin (µU/mL) ÷ 22.5. |
| Glucose tolerance | 2-hour glucose <7.8 mmol/L (140 mg/dL) | 75 g oral glucose tolerance test, every 1–3 years as your doctor advises. |
| TG/HDL ratio | <0.9 (mmol/L) · <2 (mg/dL) | From your lipid panel. |
| Waist-to-height | <0.5 | Waist at the belly button divided by height, same units. |
| SHBG and free testosterone | SHBG rising, free testosterone falling | With your doctor, same lab. Hormonal contraception changes both. |
Converted values are rounded. Hormone ranges vary by lab; your doctor reads them.
07 Where experts disagree
Where the experts don’t agree.
Everyone agrees insulin resistance is common in PCOS and that lifestyle change helps. The arguments are about how central insulin is, which diet, and whether supplements earn their place.
Is insulin the root cause of PCOS?
Insulin first: Fung
High insulin drives the ovaries to overproduce androgens. Lower insulin with diet and fasting, and much of the syndrome follows.
More than insulin: Teede, Dunaif
PCOS is strongly inherited and varies a lot between women. Insulin resistance is common and makes it worse, but some women have little of it, and androgens and the brain’s hormone signals play their own part.
Our read For most women, insulin is the biggest part you can change. Measure yours. If it’s normal, this plan will help less, and your doctor’s options matter more.
Low-carb or keto, or any healthy diet?
Low-carb: Fung, ketogenic trialists
Cutting carbs lowers insulin directly. A 2023 meta-analysis found ketogenic diets improved testosterone, SHBG and LH/FSH ratio in women with PCOS.
Any diet: the 2023 guideline
There’s no good evidence that any particular diet beats another at the same calories in PCOS. All the keto studies also produced weight loss, which could explain the results.
Our read Fewer refined carbs is common ground. Strict keto is optional. Pick the version you can keep for years, not weeks.
Is inositol worth taking?
Yes: many clinicians and patients
It’s an over-the-counter insulin sensitiser with few side effects, and small trials show better cycles and metabolic markers.
Not proven: the guideline review
The systematic review informing the 2023 guideline rated the evidence as limited and inconclusive, and called inositol experimental.
Our read Low risk, uncertain benefit. If you try it, do it with your doctor’s knowledge, one change at a time, and judge it by your cycles.
08 Limits
What no plan fixes.
Genes
PCOS runs in families. Lower insulin can quiet it, often a lot, but it doesn’t remove the tendency. It can return with weight gain, poor sleep or the old diet.
Fertility
Better insulin often brings back ovulation, but not always, and time matters. In Legro’s trial, lifestyle change before fertility treatment helped, but plenty of women still needed the treatment. If you’re trying to conceive, see your doctor early. Fertility treatment is their job.
Symptoms that need treatment
Hair growth and scalp hair loss can lag behind the numbers by many months. Very infrequent periods need your doctor to protect the lining of the uterus. Low mood and anxiety are part of PCOS and deserve care in their own right.
The plan lowers the insulin. It doesn’t replace your doctor.
09 Resources
Worth your time.
The PCOS Plan
The case for treating PCOS as an insulin problem, with low-carb eating and fasting. Read it next to the guideline, not instead of it.
Randomized controlled trial of preconception interventions in infertile women with polycystic ovary syndrome
What 16 weeks of lifestyle change did for ovulation and live births before fertility treatment. Read with your doctor if you’re trying to conceive.
International evidence-based guideline for the assessment and management of PCOS (2023)
The guideline itself, plus plain-language resources and the AskPCOS app.
10 Questions
Questions, answered plainly.
Can PCOS be reversed?
PCOS isn’t cured, but its symptoms often go into retreat. Lowering insulin and losing 5–10% of your weight, if you carry extra, often brings back regular cycles and improves skin, hair and blood sugar.
Do lean women with PCOS have insulin resistance?
Many do. Insulin resistance in PCOS happens independently of weight, though extra weight makes it worse. Get fasting insulin measured rather than assuming.
What’s the best diet for PCOS?
One built on protein, vegetables and natural fats, with little sugar or refined flour, that you can keep up. The guideline doesn’t favour any named diet; lowering insulin and sustaining it is what counts.
Will losing weight help me get pregnant?
It can. In a trial led by Richard Legro, overweight women with PCOS who spent 16 weeks losing weight before fertility treatment ovulated more often than women given only the pill beforehand, and had more live births than similar women who started treatment straight away. The programme included meal replacements and a weight-loss drug, under supervision. Don’t fast while trying to conceive, and don’t put off seeing your doctor.
Is intermittent fasting safe with PCOS?
A daily eating window is reasonable for most women, with a doctor’s OK. Skip longer fasts if you’re pregnant, trying to conceive, breastfeeding, or have a history of disordered eating.
Should I take metformin or inositol?
Ask your doctor about metformin; the guideline supports it, especially for metabolic goals. Inositol is over the counter, but the evidence is limited. Either works best on top of the plan, not instead of it.
Does exercise help PCOS?
Yes. The guideline recommends 150–300 minutes of moderate activity a week plus muscle-strengthening on two days. Muscle soaks up glucose, which means less insulin.
11 Sources
Where this comes from.
Experts drawn on
- Jason Fung, MD — Nephrologist, Toronto. Co-author of The PCOS Plan and author of The Obesity Code.
- Helena Teede, MBBS, PhD — Endocrinologist, Monash University. Led the 2018 and 2023 international PCOS guidelines.
- Andrea Dunaif, MD — Endocrinologist, Icahn School of Medicine at Mount Sinai. Leading researcher on insulin resistance and the genetics of PCOS.
- Richard Legro, MD — Reproductive endocrinologist and professor of obstetrics and gynecology, Penn State College of Medicine. Led the NIH trials of letrozole and of lifestyle change before fertility treatment in PCOS.
Sources
- Recommendations from the 2023 international evidence-based guideline for the assessment and management of polycystic ovary syndrome. Journal of Clinical Endocrinology & Metabolism, 2023.
- International evidence-based guideline for the assessment and management of polycystic ovary syndrome 2023. Monash University, 2023.
- Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications. Endocrine Reviews, 2012.
- Inositol for polycystic ovary syndrome: a systematic review and meta-analysis to inform the 2023 update of the international evidence-based PCOS guidelines. Journal of Clinical Endocrinology & Metabolism, 2024.
- Eight-hour time-restricted feeding improves endocrine and metabolic profiles in women with anovulatory polycystic ovary syndrome. Journal of Translational Medicine, 2021.
- Effects of ketogenic diet on reproductive hormones in women with polycystic ovary syndrome. Journal of the Endocrine Society, 2023.
- Letrozole versus clomiphene for infertility in the polycystic ovary syndrome. New England Journal of Medicine, 2014.
- Randomized controlled trial of preconception interventions in infertile women with polycystic ovary syndrome. Journal of Clinical Endocrinology & Metabolism, 2015.
- Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia, 1985.
Not medical advice
Discuss everything here with a medical doctor before acting on it — supplements included. Your doctor has your bloodwork and history. We have neither.