Polycystic ovary syndrome (PCOS) affects about one in ten women of reproductive age and often comes with insulin resistance, which makes weight gain easier. Losing 5–10% of body weight can improve periods, fertility and symptoms. Strength training, a protein- and fibre-rich diet, sleep and sometimes medication help most.
- There is no single “PCOS diet”; the best plan is one you can sustain.
- Exercise improves insulin sensitivity even without weight loss.
- Metformin and other medicines can help some women.
PCOS is one of the most common hormonal conditions in women, yet many go years without a diagnosis. Weight management with PCOS can feel harder, but it is very possible with the right approach.
What PCOS is
Under the international guidelines used in Canada (the Rotterdam criteria), PCOS is diagnosed when at least two of these are present, after ruling out other causes:
- Irregular or absent periods
- Signs of high androgens: excess hair growth, acne or scalp hair thinning, or raised androgen levels on blood tests
- Polycystic-appearing ovaries on ultrasound
Why PCOS affects weight
- Insulin resistance: present in many women with PCOS regardless of weight. High insulin increases androgen production by the ovaries and makes fat storage easier.
- Appetite: some research suggests altered hunger and fullness hormones.
- Fat distribution: more abdominal fat is common.
- Mood and sleep: depression, anxiety and sleep apnea are more common in PCOS and affect eating and activity.
Weight and PCOS influence each other: extra weight worsens symptoms, and PCOS makes weight harder to manage.
Nutrition
The 2023 International Evidence-based Guideline for PCOS found no single diet is superior. What matters is a sustainable calorie deficit if weight loss is the goal, and good food quality:
- Protein at every meal for fullness
- High-fibre carbohydrates: legumes, oats, whole grains, vegetables, fruit
- Fewer refined carbohydrates and sugary drinks, which raise insulin quickly
- Healthy fats from olive oil, nuts, seeds and fish
Lower-carbohydrate or Mediterranean-style diets suit many women with PCOS, but strict diets that cannot be maintained tend to backfire. See balancing blood sugar and fibre for fullness.
Exercise
Exercise improves insulin sensitivity within hours, independent of weight loss. The PCOS guideline recommends at least 150 minutes a week of moderate activity or 75 minutes of vigorous activity, plus muscle-strengthening on two days. Strength training is especially valuable because muscle is the main site of glucose uptake. See insulin sensitivity.
Sleep and stress
Women with PCOS have higher rates of sleep apnea, even without obesity. Poor sleep worsens insulin resistance and cravings. Mention snoring, daytime sleepiness or poor sleep to your doctor. Stress management and mental health support also matter. See sleep and recovery.
Medications
- Metformin: improves insulin sensitivity and may help modestly with weight and cycle regularity.
- Combined hormonal contraceptives: regulate periods and reduce androgen symptoms such as acne and hair growth.
- Anti-androgens such as spironolactone for hair growth, with contraception.
- GLP-1 medicines such as semaglutide are increasingly used for weight in women with PCOS who meet criteria. See Ozempic and Wegovy.
- Fertility treatment such as letrozole for women trying to conceive.
Inositol supplements are popular; evidence is limited and mixed.
Realistic goals
A 5–10% weight loss often restores ovulation in some women, improves cycles and reduces insulin resistance and androgen levels. Weight loss is not the only goal, though: improving fitness, blood sugar, mood and sleep brings benefits at any weight.
PCOS across life stages
PCOS symptoms often change over time. In the teenage years, irregular cycles and acne may be the main signs, and diagnosis is often delayed. During the reproductive years, fertility and weight may be the focus. After menopause, cycles stop, but the higher risk of type 2 diabetes and heart disease remains, so regular screening of blood sugar, blood pressure and cholesterol continues to matter throughout life.
Getting care in Canada
Start with your family doctor, who can order blood tests and an ultrasound and refer you to a gynaecologist or endocrinologist if needed. Dietitians, often covered by workplace benefits, can tailor eating plans. The Society of Obstetricians and Gynaecologists of Canada and PCOS-focused organisations provide patient information. See hormonal causes of weight gain.
Frequently asked questions
Why is it hard to lose weight with PCOS?
Insulin resistance, appetite changes, sleep problems and mood can all make weight loss harder, though it is very achievable.
What is the best diet for PCOS?
No single diet is best. A sustainable calorie deficit with protein, fibre and fewer refined carbohydrates works well for many women.
How much weight loss helps PCOS?
Losing 5–10% of body weight can improve cycles, ovulation, insulin resistance and symptoms.
Photo: Direct Media, StockSnap (public domain).
General information, not medical advice.
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