I see this all the time in my practice. A woman comes in with unexplained infertility. Her FSH looks fine. Her AMH is decent. Her GYN says everything looks normal. But her fasting insulin is 18. Her HbA1c is 5.6. And nobody has connected the dots.

Metabolic dysfunction is one of the most common — and most correctable — drivers of impaired fertility I see. Most conventional fertility workups often miss it. And it’s one of the reasons why in my practice we have been so successful in helping women get pregnant, if they are willing to take a few months to prepare for optimal conception first. 

Here's what the research shows, and how to set up your metabolic health for greater fertility success.

Insulin resistance silently disrupts ovulation, egg quality, and implantation — often before any cycle irregularity appears.

The Metabolic Fertility Reset:

❌ The old assumption: Metabolic dysfunction and PCOS only affect women who are overweight or have irregular cycles.

✅ The new reality: Insulin resistance affects lean women with PCOS too — and it impairs fertility independent of body weight. A systematic review found a 27% intrinsic reduction in insulin sensitivity in PCOS patients regardless of BMI (Human Reproduction, 2016). You can look normal on a standard panel and still be metabolically impaired.

❝ Insulin resistance disrupts the HPO axis — the hormonal control center for ovulation — even when cycles appear regular.

🩸 How insulin hijacks your hormones Elevated insulin tells your ovaries to produce more androgens (testosterone, DHEA). That surge suppresses ovulation, impairs egg maturation, and degrades uterine lining quality. It also flattens the natural LH surge that triggers ovulation — even in women who don't have PCOS.

🥚 What this does to egg quality Eggs are the most mitochondria-dense cells in the body. In lean, non-PCOS women with insulin resistance (IR), the percentage of mature oocytes and blastocyst formation rate were both significantly lower than in women without IR (Frontiers in Endocrinology, 2021). This isn't just a PCOS problem.

🧬 Blood sugar and implantation Even after fertilization, the uterine environment matters. Insulin resistance is associated with impaired endometrial receptivity — the lining's ability to accept an embryo. Correcting IR before IVF significantly improved live birth rates in one retrospective cohort (Human Reproduction, 2025).

2️⃣ Prioritize protein at every meal — especially your first. Aim for 25–35g protein per meal. Protein first stabilizes the cortisol and glucose spike that happens in the morning, which sets the hormonal tone for the entire day.

3️⃣ Cut the sugar — including the sneaky sources. Under 25g added sugar daily. That means reading labels on yogurt, granola, "healthy" sauces, and protein bars. Sweetened coffee drinks often contain 30–40g in one serving!

4️⃣ Move after meals. A 10-minute walk after eating meaningfully lowers post-meall glucose — as effectively as a 30-minute session in some studies (Sports Medicine, 2022). This is the simplest metabolic intervention there is. No gym required.

5️⃣ Consider a CGM. Two weeks of continuous glucose monitoring will show you which foods spike your blood sugar, how your stress affects glucose, and whether your overnight fasting glucose is truly stable. This is data your doctor will never get from a fasting lab draw alone.

6️⃣ Add targeted supplements if indicated.

The goal: stable blood sugar, regular ovulation, a follicular environment where egg quality can thrive.

Does this resonate? Hit reply — I read every response!

The past few days were a lot for my mom-heart.

On Sunday we dropped my 9-year-old at sleepaway camp for four weeks. Today my 4-year-old graduated from preschool — my last baby is headed to kindergarten in the fall, and seven straight years of walking children to our beloved Brooklyn Montessori is coming to a close.

I still remember dropping off my oldest for his first morning there when he was two. I was wrecked with anxiety. Isn't he too young to be institutionalized? I freaked out to my husband. I sat with him on the floor, introducing him to his new surroundings — elegantly designed wooden puzzles the guides called "work" that made the church basement preschool I attended at his age look prehistoric. What did we even do in there? I'm pretty sure few fine motor skills were developed.

So yesterday, crying at camp while my oldest took it all in with calm and confidence, I found myself worrying again: What if he has a hard time with friends? What if they only eat terrible food? How will he sleep in an open cabin? And then I remembered: we have taught him resilience. He knows how to find his way.

In midlife, I'm asking myself the same question. Changes are happening — ones I can't avoid or control. Do I know how to find my way? How resilient am I? How will I adapt when the things that used to work don't, or when a chapter closes that I can't reopen no matter how much I want to? I can only use what it taught me and look forward, with an open mind and an open heart.

Thankfully, I have tools now that I didn't have at four or nine. Books, friends, colleagues, great doctors and coaches and therapists, meditation and yoga and exercise, too many supplements, and a deep sense of who I am. In my pursuit of longevity, I'm not just optimizing — I'm using these tools to adapt to life's changes. And I'm happy to report: they work pretty well.

The first thing I do for any woman trying to conceive is run a complete metabolic picture — fasting insulin, HbA1c, Omega-3 index, hsCRP, and a full hormone panel timed to her cycle. Not a basic OB workup. A functional medicine workup that actually finds what's driving the problem.

Stay strong, stay curious, and breathe,

Robin

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As always, this newsletter is for informational and educational purposes only and is not intended as medical advice. Always consult your healthcare provider before making any health decisions or changes to your treatment plan.