Podcast Summary: The Dr. Gabrielle Lyon Show
Episode: The Menstrual Cycle DECODED: Fertility, PCOS, and the New Science of Hormones
Date: October 28, 2025
Host: Dr. Gabrielle Lyon
Guest: Dr. Heidi (reproductive physiologist and researcher)
Episode Overview
This episode delivers a deep dive into the science of the menstrual cycle, fertility, PCOS (Polycystic Ovary Syndrome), and current research on reproductive hormones and ovarian physiology. Dr. Lyon and her expert guest, Dr. Heidi, break down complex myths, demystify phases of the cycle, discuss fertility challenges, and share new discoveries about ovarian function and the gut microbiome’s impact on reproductive health. The conversation emphasizes empowering education for all listeners—regardless of gender or background.
Key Discussion Points & Insights
1. Foundations: The Menstrual, Ovarian, and Uterine Cycles
- Distinction between cycles:
- The menstrual cycle involves coordinated, but distinct, changes in the ovaries (“ovarian cycle”) and uterus (“uterine cycle”). (00:03–00:44)
- Uterine cycle phases:
- Menstruation (shedding of endometrial lining)
- Proliferative phase (thickening and rebuilding due to estrogen from the ovary)
- Secretory phase (preparation for implantation; driven by progesterone after ovulation) (04:44–06:29)
- Ovarian cycle explanation:
- Multiple follicles (eggs) begin developing at the same time; one is selected to grow and ovulate, while others regress (atresia). (06:35–11:16)
- Selection is influenced by hormone signaling (FSH, then LH as the follicle matures). (12:01–13:13)
- Follicle “waves”:
- Most women typically have two “waves” of follicle growth per cycle; some have three. Only one usually leads to ovulation. (19:08–20:05)
2. Variability in Menstrual and Ovarian Cycles
- 28-day cycle is not the universal norm:
- “It's not as common as we think it is.” (14:44–14:47)
- Cycle regularity ≠ ovulatory regularity:
- Regular periods do NOT guarantee regular ovulation, especially during adolescence, obesity, or hypothalamic amenorrhea. (14:58–16:11)
- Adolescence & post-menarche changes:
- It can take years after the first period (menarche) for regular, ovulatory cycles to establish. (16:11–16:41)
- Obesity and luteal phase defects:
- Women with regular periods but obesity may still have impaired ovulation (“luteal phase defects”) affecting fertility. (17:19–18:21)
- Early menarche (before 10–12 years):
- Associated with increased risks for type 2 diabetes, obesity, endometrial cancer, and more. (46:01–47:46)
3. Fertility, Ovulation “Windows,” and Menopause Transition
- Can you get pregnant on your period?
- Rare, but possible. “I’ve seen ovulation during menses.” (01:09, 01:54, 02:01)
- Late reproductive years & “rogue follicles”:
- Just before menopause, follicles may grow and ovulate at unexpected times, related to decreased ovarian “brakes” like AMH (anti-müllerian hormone). (35:32–38:05)
- Predicting menopause:
- Number of remaining follicles is loosely predictive, but no precise predictor currently in clinical use. Genetics play a powerful role. (39:04–41:21)
- Ovary as a biomarker:
- Ovarian morphology on ultrasound can reflect undernutrition, obesity, PCOS, or healthy status—and possibly overall metabolic health. (24:46–26:53)
4. Nutrition, Myths & Evidence-Based Recommendations
- No dietary cure for PCOS:
- “There really isn’t data to suggest that diet can cure PCOS. There is no cure for PCOS right now.” (13:30, 62:43)
- Fruit and PCOS:
- “You shouldn’t eat fruit if you have PCOS because it makes your insulin resistance worse? … Data actually show the exact opposite.” (00:27, 59:16)
- Seed cycling & changing diet with menstrual phases:
- “Seed cycling is a myth. We do not have evidence for that… I have not seen convincing evidence that would support [changing nutrition during the cycle] is a good idea.” (59:41–61:28)
- Balancing hormones with food or supplements:
- “The notion that you can balance your hormones … it doesn’t physiologically make a lot of sense to me. That one is a myth.” (63:03)
- Fish oil (EPA/DHA) and menstrual cramps:
- “There is pretty good evidence to suggest that fish oils … can be beneficial for alleviating [menstrual cramps] … relates to inflammation in the endometrial lining.” (64:21–66:38)
- Dairy and inflammation/PCOS:
- “Dairy causes inflammation which makes PCOS worse? Not something I’ve seen data to support.” (67:42–67:56)
- Microbiome and the menstrual cycle:
- New rodent studies suggest that secondary bile acids (from the gut) interact with the brain to potentially advance puberty and influence reproductive health. Early human data support similar associations. (68:35–71:52)
5. Empowering Listeners: What Everyone Should Know
- Female reproductive development is adaptable and sensitive:
- Ovulation, menstruation, and fertility are influenced by nutrition, metabolic status, environment, and genetics.
- Irregularity is normal in many life phases:
- Both in teens (after menarche) and during the years leading up to menopause (perimenopause).
- Common fertility challenges:
- Not just with ovulation—men may experience sperm quality issues, and women’s cycles can reflect complex disturbances.
Notable Quotes & Memorable Moments
On Scientific Rigor in Women's Health
“I think just the basic understanding of filling in our gaps about how human physiology works. I think it’s also helpful to give women answers and give parents and teenagers answers to why they might be experiencing symptoms across their menstrual cycle. Knowledge is power…”
— Dr. Heidi (22:55)
On the Reality of Cycle Tracking Apps
“I think it’s not helped by certain apps that exist that tell women what they should be feeling like … again benchmarked against this sort of textbook case. We know that there is tremendous amounts of intra- and inter-individual variability…”
— Dr. Heidi (44:10)
On the “Myth” of Seed Cycling and Diet Timing
“Seed cycling is a myth. We do not have evidence for that.”
— Dr. Heidi (61:06)
On Early Menarche & Health Outcomes
“Earlier timing of first menarche is and has been associated with a whole host of cardiometabolic and reproductive diseases later in life.”
— Dr. Heidi (47:46)
On the “Cure” for PCOS via Diet
“There really isn’t data to suggest that diet can cure PCOS. There is no cure for PCOS right now.”
— Dr. Heidi (62:43)
On Fish Oil and Menstrual Cramps
“There is pretty good evidence to suggest that, you know, the fish oils, the DHA, EPA, they can be beneficial for alleviating [menstrual cramps]…”
— Dr. Heidi (64:49)
Key Timestamps for Reference
- 00:03: Introduction to ovarian and uterine cycles
- 04:44–06:29: Detailed anatomy & function of uterine cycle
- 06:35–11:16: Follicle development and selection process
- 14:58–16:41: The reality of adolescent cycle variability
- 17:19: Obesity and regular cycles: hidden fertility challenges
- 19:08: Understanding “waves” of follicle development
- 24:46–26:53: Ovarian morphology as a health indicator
- 35:32: Menopausal transition and “rogue follicles” discovery
- 46:01: Age at menarche and health implications
- 59:41: Debunking seed cycling
- 62:43: Can diet “cure” PCOS?
- 64:49: Fish oil and menstrual cramps
- 68:35: Microbiome, bile acids, and reproductive axis connection
Additional Insights
- Clinical implications:
- Leveraging new knowledge of follicle waves could optimize assisted reproductive technology protocols and timing. (20:16)
- Nutrition guidelines:
- Best evidence supports following established national dietary guidelines for overall and reproductive health.
- Menstrual variability:
- A “disrupted” cycle can be entirely benign or an early sign of metabolic or endocrine disturbance—context is vital.
Conclusion
Dr. Lyon and Dr. Heidi provide a rare, evidence-based look into the realities, myths, and marvels of the menstrual cycle. The episode is rich with practical information, myth-busting, and a call for greater transparency, research, and education in women’s health. Listeners are left empowered with scientific understanding—and motivated to ask smarter questions, seek quality care, and dismiss pseudoscientific diet fads for evidence-based actions.