PCOS and Insulin Resistance

Written By Alexia Sammut Scotto

Why the Carbs You Eat Matter?

If you’ve been diagnosed with PCOS, you’ve probably read about insulin resistance more times than you can count. But what does it really mean? And why do so many women with PCOS struggle with it — even those who are slim, active, and eat “pretty healthy”?

The truth is, insulin resistance is incredibly common in PCOS. In fact, research suggests it affects up to 75% of lean and 95% of overweight or obese women with PCOS (Spritzer et al., 2024). It’s not just about weight — your hormones, genetics, and lifestyle can all play a role.

Insulin Resistance in Real Life

In simple terms, insulin is like a key that helps move sugar from your blood into your cells, where it’s used for energy. But when you have insulin resistance, that “key” doesn’t work as well. Your body tries to compensate by making more insulin.

Over time, those high insulin levels can:

  • Push your ovaries to make more androgens (male hormones)

  • Disrupt ovulation

  • Affect egg quality

  • Increase inflammation

You might notice symptoms like:

  • Fatigue, especially after meals

  • Sugar cravings that feel impossible to resist

  • Unexplained weight gain around your middle

  • Irregular or missing periods

  • Acne or excess hair growth

  • Skin tags or dark, velvety patches of skin

But here’s the tricky part — not everyone with insulin resistance feels these symptoms. That’s why testing (fasting insulin, glucose tolerance, or HOMA-IR) can be so helpful.

Why This Matters for Fertility

When insulin resistance is present, it can make the delicate balance of reproductive hormones even harder to maintain. Elevated insulin stimulates the ovaries to produce more testosterone, which can interfere with ovulation (Purwar & Nagpure, 2022). Without regular ovulation, cycles can become long, irregular, or disappear altogether — making conception harder, whether naturally or with IVF.

What the Research Says About Carbohydrates

Carbohydrates aren’t “bad” — in fact, your body and brain need them. But in PCOS, both the quantity and quality of carbs can make a big difference.

Quantity: How Much is Enough?

Several clinical trials have tested diets where 30–40% of total calories come from carbs — much less than the 50–55% in a typical diet — and found real benefits:

  • An isocaloric 40% carb diet over 12 weeks improved insulin sensitivity and restored menstrual regularity (Moran et al., 2013).

  • Similar moderate-carb approaches have improved inflammation, body composition, and insulin sensitivity (Gower et al., 2013).

That said, there’s no single “magic” percentage that works for everyone. The right carb level depends on your health, activity, and what feels sustainable for you.

Quality: Low GI for the Win

While the amount of carbs matters, the type you choose may matter even more. Studies show that a low glycaemic index (GI) diet — one based on carbs that release glucose slowly — can improve insulin sensitivity and even restore regular cycles in PCOS (Kazemi et al., 2020).

Low-GI foods help prevent big spikes in blood sugar and insulin, which reduces stress on your hormonal system.

Examples of low-GI, high-fibre carbs include:

  • Whole grains: steel-cut oats, quinoa, buckwheat, pearl barley

  • Legumes: lentils, chickpeas, black beans, kidney beans

  • Fruits: berries, apples, pears, cherries

  • Vegetables: sweet potato, carrots, leafy greens, peppers

  • Other: wholegrain pasta, rye bread, basmati rice (in moderation)

A Balanced, Sustainable Approach

From my work with clients — and my own experience — I’ve seen that the best results happen when we combine:

  • Moderate carb intake (often 30–40% of calories) tailored to the individual

  • Low-GI, high-fibre carb choices at most meals

  • Balanced protein and healthy fats to slow digestion and keep blood sugar stable

  • Lifestyle factors like movement, stress management, and good sleep

PCOS is complex. There’s no one-size-fits-all plan — but by finding your personal balance of how much and what kind of carbohydrates you eat, you can make a real difference in your insulin sensitivity, hormone balance, and fertility outcomes.

Final Note: Nutritional changes work best when personalised. If you have PCOS and suspect insulin resistance, working with a qualified nutritional therapist can help you create a tailored plan that supports blood sugar balance, hormone health, and fertility.

References:

  • Purwar A, Nagpure S. Insulin Resistance in Polycystic Ovarian Syndrome. Cureus. 2022;14(10):e30351. Published 2022 Oct 16. doi:10.7759/cureus.30351

  • Moran LJ, Noakes M, Clifton PM, Tomlinson L, Galletly C, Norman RJ. Dietary composition in restoring reproductive and metabolic physiology in overweight women with polycystic ovary syndrome. J Clin Endocrinol Metab. 2003;88(2):812-819. doi:10.1210/jc.2002-020815

  • Gower BA, Goss AM. A lower-carbohydrate, higher-fat diet reduces abdominal and intermuscular fat and increases insulin sensitivity in adults at risk of type 2 diabetes. J Nutr. 2015;145(1):177S-83S. doi:10.3945/jn.114.195065

  • Kazemi M, Hadi A, Pierson RA, Lujan ME, Zello GA, Chilibeck PD. Effects of Dietary Glycemic Index and Glycemic Load on Cardiometabolic and Reproductive Profiles in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Adv Nutr. 2021;12(1):161-178. doi:10.1093/advances/nmaa092

Alexia Sammut Scotto
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