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Guide · by Alexandra Lasconi

Have you been diagnosed with PCOS, fibroids or endometriosis?

Or does your doctor suspect one of them? Then losing weight is not the first step. With PCOS, fibroids or endometriosis, low iron, low vitamin D, a slow thyroid, insulin that runs high and poor oestrogen clearance are common, and each of them makes fat loss harder and makes you feel worse. So before we touch your calories, we find out what your body is missing, support the way your gut and liver clear hormones, fill the gaps with food first, and only then plan a fat-loss phase. This page shows what to check, why, and what to change.

Bring this page to your doctor. They diagnose, decide which tests are right for you and read the results. Working with me? Do the tests before day 1 of your plan and send me the results.
01

I have PCOS

Insulin, androgens, thyroid and vitamin D: what to check and how it shapes your carbs, protein and training.

 02

I have fibroids

Heavy periods drain iron. What to check, how often, and what to eat to rebuild your stores.

 03

I have endometriosis, or my doctor suspects it

Inflammation, pain and iron loss: what to check and how to eat without cutting out food groups.

 04

What they share

Oestrogen clearance, your gut and your liver: the system behind heavy, painful periods and severe PMS.

Many women have more than one. Read every section that applies to you, then sections 04 to 07: they apply to all three.

01 · If you have PCOS

In most women PCOS is driven by insulin resistance, by excess androgens (testosterone and related hormones), or by both. Your blood tests show which one leads in your case, and that decides how I set your carbohydrates, protein and training. When ovulation is rare, little progesterone is made, so oestrogen goes unbalanced: that is why oestrogen clearance (section 04) matters for PCOS too.

What it means for how you eat

  • Carbs are not the enemy. We place them around training and pair them with protein and fibre instead of cutting them out.
  • Protein at every meal keeps appetite and blood sugar steadier through the day.
  • Strength training builds the muscle that takes up most of the glucose you eat.

What often runs low

  • Vitamin D is low in most women with PCOS.
  • Vitamin B12 falls over time if you take metformin.
  • Iron can drop if cycles are long and then heavy.

Blood tests for PCOS

TestWhy it mattersOptimal for a woman who trainsWhen
Fasting insulinThe earliest sign of insulin resistance, years before glucose rises.Under 8 µIU/mL (under 56 pmol/L). Above 12 suggests insulin resistance.Baseline, then every 3 months
HOMA-IROne number for insulin resistance, calculated from fasting insulin and glucose.Under 1.5. Above 2.5 is insulin resistant.With fasting insulin
2-hour glucose tolerance test (75 g OGTT)Picks up glucose problems fasting tests miss; recommended for every woman with PCOS.2-hour glucose under 140 mg/dL (7.8 mmol/L). Over 200 is diabetes.Baseline, then every 1 to 3 years
Total and free testosteroneConfirms androgen excess, the core feature of PCOS.Total under 50 ng/dL (1.7 nmol/L). Free testosterone in the lower half of your lab's range.Baseline, then every 6 months
SHBGLow SHBG means more free testosterone and is itself a marker of insulin resistance.Above 50 nmol/L. Below 30 points to insulin resistance.With testosterone
DHEA-S and androstenedioneShow whether the extra androgens come from the adrenals or the ovaries.Within your lab's range for your age.Baseline
17-hydroxyprogesterone (17-OHP)Rules out non-classic adrenal hyperplasia, which mimics PCOS.Under 200 ng/dL (6 nmol/L), cycle days 2 to 5, morning.Baseline
LH and FSHA high LH-to-FSH ratio is typical of PCOS.LH-to-FSH ratio under 2:1. Cycle days 2 to 5.Baseline
ProlactinRules out a pituitary cause of missed periods.Under 25 ng/mL (530 mIU/L).Baseline
TSH (with free T4 if abnormal)Thyroid problems mimic PCOS, slow fat loss and disturb cycles.0.5 to 2.5 mIU/L.Baseline
AMHOften high in PCOS; useful if periods are irregular or you plan a pregnancy.Your gynaecologist interprets it; supportive, not diagnostic.Baseline, if advised
Vitamin D (25-OH-D)Low in most women with PCOS; linked to insulin resistance and irregular cycles.40 to 60 ng/mL (100 to 150 nmol/L). Below 20 is deficient.Baseline, then every 3 months if low
Pelvic ultrasound (transvaginal)Shows ovarian volume and follicle count. Not needed if androgens are high and cycles irregular.Your gynaecologist interprets it.Baseline, if advised
On the pill? Hormone tests (testosterone, SHBG, DHEA-S, LH, FSH, 17-OHP) are only reliable after at least 3 months off hormonal contraception. Tell your doctor; they decide whether to test now or later.

02 · If you have fibroids

Fibroids are common and often harmless in themselves, and they grow in response to oestrogen and progesterone. What matters for your energy and your training is what they can do month after month: heavy periods drain iron, and low iron makes you tired, weaker in the gym and slower to recover, long before a standard blood count shows anaemia. Low vitamin D is also consistently linked to fibroids.

What it means for how you eat

  • Iron-rich food every day: red meat, fish, eggs, lentils, beans and dark leafy greens, with vitamin C (citrus, peppers, berries) at the same meal.
  • Tea and coffee between meals, not with them: they reduce iron absorption.
  • Iron supplements only with your doctor, dosed from your ferritin.

What to watch

  • Ferritin falls first, long before haemoglobin.
  • Vitamin D, especially through winter.
  • Thyroid: an underactive thyroid can make bleeding heavier and fat loss slower.

Blood tests for fibroids

TestWhy it mattersOptimal for a woman who trainsWhen
Full blood count (FBC/CBC)Shows whether heavy bleeding has caused anaemia.Haemoglobin 13 to 15 g/dL (below 12 is anaemia). MCV 82 to 98 fL. Platelets 150 to 400.Every 8 to 12 weeks
FerritinIron stores. Falls long before haemoglobin does.50 to 100 ng/mL. Below 30 is iron deficiency.Every 8 to 12 weeks
Transferrin saturation and CRPConfirm the iron picture; inflammation can hide low iron.Saturation 20 to 45%. CRP below 3 mg/L (hs-CRP ideally below 1).With ferritin
Vitamin D (25-OH-D)Low vitamin D is consistently linked to fibroids.40 to 60 ng/mL (100 to 150 nmol/L). Below 20 is deficient.Baseline, then every 3 months if low
TSH (with free T4 if abnormal)Thyroid problems cause heavy bleeding and slow weight loss.0.5 to 2.5 mIU/L.Baseline
Pelvic ultrasound (transvaginal)The only way to see number, size and location. Cycle days 5 to 10.Your gynaecologist interprets it.Baseline, then as advised
No blood test can measure your fibroids. The ultrasound does that; the blood tests show what they are costing you.

03 · If you have endometriosis, or your doctor suspects it

Endometriosis means tissue similar to the lining of the womb grows outside it, most often in the pelvis. It depends on oestrogen and it is inflammatory: that is where the pain, heavy or painful periods, pain with sex or bowel movements, bloating and fatigue come from. It affects around 1 in 10 women of reproductive age and often takes years to diagnose. Your gynaecologist confirms it with a specialist ultrasound or MRI, sometimes laparoscopy. Nutrition does not remove endometriosis, but it can lower the inflammatory load, protect your iron and support the way your body clears oestrogen.

What it means for how you eat

  • Omega-3 fats from oily fish (salmon, sardines, mackerel) two to three times a week. In a large Harvard cohort, women eating the most long-chain omega-3 had a lower risk of endometriosis.
  • Colour and fibre at every meal: vegetables, fruit, legumes, whole grains, nuts and seeds bring antioxidants and feed the bacteria that help clear oestrogen.
  • Enough protein for your gut lining and your liver (sections 04 and 05).
  • No food groups cut out by default. Some women find certain foods trigger bloating; we test one change at a time, with a dietitian if needed, instead of removing everything at once.

What often runs low

  • Iron, from heavy periods.
  • Vitamin D, linked to inflammation and pain.
  • Omega-3, when oily fish is rare.
  • Magnesium, often low with poor sleep, stress and heavy training.

Blood tests for endometriosis

TestWhy it mattersOptimal for a woman who trainsWhen
Full blood count (FBC/CBC)Shows whether heavy bleeding has caused anaemia.Haemoglobin 13 to 15 g/dL (below 12 is anaemia).Baseline, then every 3 months if periods are heavy
FerritinIron stores; the first thing heavy periods use up.50 to 100 ng/mL. Below 30 is iron deficiency.Baseline, then every 3 months if periods are heavy
CRP (hs-CRP)A general marker of inflammation, and needed to read ferritin correctly.hs-CRP ideally below 1 mg/L.With ferritin
Vitamin D (25-OH-D)Low levels are common and linked to inflammation.40 to 60 ng/mL (100 to 150 nmol/L). Below 20 is deficient.Baseline, then every 3 months if low
TSH (with free T4 if abnormal)Thyroid problems add to fatigue and heavy bleeding.0.5 to 2.5 mIU/L.Baseline
Specialist ultrasound or MRIHow endometriosis is actually seen and mapped.Your gynaecologist orders and interprets it.As advised
No blood test diagnoses endometriosis. CA-125 is not recommended for diagnosis by the European guideline (ESHRE). Tell your doctor about every symptom, including bowel or bladder pain with your period.

04 · What they share: oestrogen clearance, your gut and your liver

You may have heard the phrase "oestrogen dominance". It is not a medical diagnosis, but it describes something real: oestrogen that is high relative to progesterone, or oestrogen that is not cleared efficiently. Fibroids and endometriosis depend on oestrogen. In PCOS, rare ovulation means little progesterone to balance it. So in all three, how well your body clears oestrogen matters, and that is a system: your liver, your gut and the protein and fibre you eat every day.

1. The liver packages oestrogenIn phase II, the liver attaches small molecules to used oestrogen (methylation, glucuronidation, sulfation, glutathione) so it can leave the body. These steps need amino acids from protein (glycine, cysteine, methionine), plus B vitamins, folate and magnesium.
2. The gut carries it outPackaged oestrogen goes into bile and out through the bowel. Enough fibre, and enough variety of fibre, keeps it moving and binds part of it.
3. Gut bacteria decide how much returnsSome gut bacteria make an enzyme (beta-glucuronidase) that unpacks oestrogen so it is re-absorbed. Scientists call this group of bacteria the estrobolome. A low-fibre, less diverse microbiome tends to send more oestrogen back.
4. The gut lining decides what gets throughA weak gut lining lets bacterial fragments into the blood, which adds to inflammation, the same inflammation that drives pain in endometriosis.

Where the evidence stands: the liver pathways and the role of fibre in oestrogen excretion are well established. The estrobolome is newer science: studies in women with endometriosis and other oestrogen-related conditions are promising but still small.

Signs that oestrogen may not be well balanced

  • Water retention and bloating before your period.
  • Heavy periods, or periods with clots.
  • Painful periods that stop you training or working.
  • Severe PMS: mood swings, irritability, cravings, poor sleep before your period.
  • Breast tenderness or swelling.
  • Fibroids or endometriosis themselves.

These signs have other causes too, so they are a reason to talk to your doctor, not a diagnosis.

05 · Your gut needs more than probiotics to regain its function

Probiotics are the tenants. Your gut lining is the house, and fibre is the food. Adding tenants to a damaged house with an empty fridge does not work for long. So the order is: repair the lining first, feed the bacteria second, and only then, where useful, add probiotics or fermented foods.

What the lining is

One single layer of cells, held together by tight junctions and covered by a protective mucus layer, with the immune system right underneath. The cells renew every 3 to 5 days, so what you eat this week builds next week's lining.

What it needs

Protein: glutamine is the main fuel of small-intestine cells; threonine, serine and proline build the mucus layer. Fibre: bacteria turn it into butyrate, the main fuel of colon cells. Vitamins A and D, and zinc keep the tight junctions sealed. Omega-3 and colourful plants calm inflammation.

What damages it

Too little fibre (bacteria then feed on the mucus layer instead), too little protein, alcohol, frequent painkillers such as ibuprofen (discuss with your doctor), chronic stress, short sleep and a lot of ultra-processed food.

  • Fibre variety, not just amount. Aim for many different plants across the week: vegetables, fruit, legumes, whole grains, nuts, seeds, herbs and spices all count. People eating a wider variety of plants have a more diverse microbiome.
  • Fermented foods such as yogurt, kefir, sauerkraut and kimchi are an everyday way to add bacteria. In a Stanford trial they increased microbiome diversity and lowered inflammatory markers.
  • Probiotic supplements work strain by strain and mostly stay only while you take them and feed them. Use them for a reason, not as the foundation.
  • "Leaky gut" tests (such as zonulin) are not reliable, so we do not use them. We look at your habits, your symptoms and your standard blood tests instead.

Where the evidence stands: fibre and butyrate, and vitamin D and zinc for the barrier, are well supported. Glutamine supplements give mixed results in people; glutamine from enough food protein is the safe base.

06 · Find the habits that brought you here

Lifestyle is one of the main drivers of all of this. Answer honestly; every "no" is something we can change.

HabitAsk yourselfWhy it matters
FibreDo I eat vegetables, fruit, legumes or whole grains at most meals, and many different ones across the week?Feeds the bacteria, carries oestrogen out, protects the mucus layer.
ProteinDo I have a real protein source at every meal?Amino acids for the gut lining and for liver phase II. Set your number with the macros calculator.
AlcoholDo I drink more than a couple of times a week?Weakens the gut lining and competes with oestrogen clearance in the liver.
SleepDo I sleep 7 to 9 hours most nights?Short sleep raises inflammation and cravings and weakens the gut barrier.
StressDo I have daily ways to come down from stress?Chronic stress changes gut bacteria and loosens the lining.
MovementDo I train for strength and walk most days?Improves insulin sensitivity and helps keep body fat, a source of oestrogen, in a healthy range.
Processed foodIs most of what I eat ultra-processed?Usually low in fibre and nutrients, high in additives that can affect the lining.

07 · Why we fix the gaps before cutting calories

A calorie deficit means less food, and less food means fewer nutrients coming in. If your iron, vitamin D or B12 are already low, or your protein and fibre are already short, a deficit pushes you further down: more fatigue, harder training, more hair loss, stronger cravings, heavier PMS and slower results. Building your intake up first is not a delay. It is what makes the fat-loss phase work.

1. TestThe blood tests on this page, read by your doctor.
2. Build upEat at maintenance: protein at every meal, many different plants, while your doctor corrects any deficiency.
3. RetestFerritin and vitamin D again after 8 to 12 weeks.
4. Then lose fatA moderate phase with the phase planner, protein high, training kept.
We stay at maintenance, and your doctor treats it first, if: your ferritin is below 30 ng/mL, your haemoglobin is low, your vitamin D is below 20 ng/mL, your TSH is outside 0.5 to 4.0 mIU/L, your HbA1c is 6.5% or above, your 17-OHP, prolactin or cortisol is abnormal, your periods are getting heavier, or your pain is not controlled.

08 · Your blood test checklist

For everyone, with PCOS, fibroids or endometriosis

Baseline now, then once a year. With PCOS, treat the glucose and lipid markers as a 6-month check: the risk of type 2 diabetes and heart disease is higher.

TestOptimal for a woman who trains
HbA1cUnder 5.4% (5.7% and above is prediabetes)
Fasting glucose70 to 90 mg/dL (3.9 to 5.0 mmol/L)
LDL cholesterolUnder 100 mg/dL (2.6 mmol/L)
HDL cholesterolAbove 60 mg/dL (1.5 mmol/L)
TriglyceridesUnder 100 mg/dL (1.1 mmol/L). Above 150 with low HDL points to insulin resistance.
ALT and AST (liver)Under 25 U/L. Raised ALT with PCOS can mean fatty liver.
Creatinine and eGFR (kidney)Creatinine 0.6 to 1.1 mg/dL, eGFR above 90. Training and high protein can raise creatinine slightly.
Vitamin B12Above 400 pg/mL (300 pmol/L). Every 6 months if you take metformin.
FolateAbove 10 ng/mL
Magnesium0.85 to 1.0 mmol/L (2.0 to 2.4 mg/dL)

Add if you have PCOS

Fasting insulin and HOMA-IR, 2-hour glucose tolerance test, total and free testosterone, SHBG, DHEA-S and androstenedione, 17-OHP, LH and FSH, prolactin, TSH, vitamin D; AMH and ultrasound if advised. Details above.

Add if you have fibroids

Full blood count, ferritin, transferrin saturation and CRP, vitamin D, TSH, and a pelvic ultrasound. Details above.

Add if you have endometriosis

Full blood count, ferritin, hs-CRP, vitamin D, TSH, and the imaging your gynaecologist orders. Details above.

Only if your doctor thinks it is needed

  • A pregnancy test, before starting any new treatment.
  • Clotting tests (including von Willebrand) if you have always had very heavy periods or bleed easily.
  • Morning cortisol if you have rapid weight gain, purple stretch marks or very high blood pressure.
  • Lipoprotein(a) and ApoB once, if you have PCOS and a family history of early heart disease.
  • A sleep study if you snore or wake unrefreshed; sleep apnoea is common with PCOS.
  • AMH and fertility tests if you are planning a pregnancy.

09 · How to prepare for the test

  • Go in the morning, fasting 10 to 12 hours (water only), and not the day after a hard training session.
  • Cycle-dependent hormones (LH, FSH, 17-OHP, testosterone) are best drawn on cycle days 2 to 5. With very irregular or absent periods, any day works; tell your doctor the date of your last period.
  • Stop biotin supplements (hair, skin and nails products) 72 hours before: biotin interferes with hormone and thyroid results.
  • Routine oestrogen and progesterone panels are not needed to manage fibroids, endometriosis or PCOS.
  • Labs use different units and ranges. The optimal ranges on this page are a guide for women who train; your doctor has the final word.

For the full picture of iron, vitamin D and the other markers every woman who trains should know, see Blood tests for women who train. To rebuild your gut step by step, see the Gut rebuild guide.

Sources

  1. International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome 2023 (Monash University, ESHRE, ASRM).
  2. Becker CM et al. ESHRE guideline: endometriosis. Hum Reprod Open (2022).
  3. NICE. Endometriosis: diagnosis and management (NG73, updated 2024).
  4. Meneghetti JK et al. Effect of dietary interventions on endometriosis: a systematic review and meta-analysis of randomized controlled trials. Reprod Sci (2024).
  5. Missmer SA et al. A prospective study of dietary fat consumption and endometriosis risk (Nurses' Health Study II, Harvard). Hum Reprod (2010).
  6. Baker JM, Al-Nakkash L, Herbst-Kralovetz MM. Estrogen-gut microbiome axis: physiological and clinical implications. Maturitas (2017).
  7. Saponara et al. Could the estrobolome have a role in endometriosis pathogenesis and infertility? A systematic review. BMC Womens Health (2026).
  8. Tsuchiya Y, Nakajima M, Yokoi T. Cytochrome P450-mediated metabolism of estrogens and its regulation in human. Cancer Lett (2005).
  9. Gaskins AJ et al. Effect of daily fiber intake on reproductive function: the BioCycle Study (NIH). Am J Clin Nutr (2009).
  10. Desai MS et al. A dietary fiber-deprived gut microbiota degrades the colonic mucus barrier and enhances pathogen susceptibility. Cell (2016).
  11. Camilleri M. Leaky gut: mechanisms, measurement and clinical implications in humans. Gut (2019).
  12. Kim MH, Kim H. The roles of glutamine in the intestine and its implication in intestinal diseases. Int J Mol Sci (2017).
  13. Wastyk HC et al. Gut-microbiota-targeted diets modulate human immune status (Stanford). Cell (2021).
  14. McDonald D et al. American Gut: an open platform for citizen science microbiome research. mSystems (2018).
  15. Australian Commission on Safety and Quality in Health Care. Heavy Menstrual Bleeding Clinical Care Standard (2024).
  16. Ivanova et al. Vitamin D and uterine fibroids. J Obstet Gynaecol Can (2024).
  17. American Society of Hematology. Iron deficiency guideline (draft, 2025).

This page is nutrition coaching information, not medical advice. Your doctor diagnoses, treats and reads your results; talk to them before changing medication or supplements.

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