Hormones, glucose, and insulin: what Jay Shetty's guest probably got right and wrong

What did @jayshettypodcast actually say?

The claim is that insulin levels can shift meaningfully "in three days" through food and exercise changes, that estrogen and progesterone take "four to six weeks" to adjust, and that women with high testosterone can lower their levels within seven days by reducing carbohydrates. These are specific, time-bound promises attached to dietary changes, and they were presented as straightforward and reassuring rather than conditional.

To be fair to the framing: the intent was to push back against fatalism, the idea that hormonal change takes years and feels impossible. That's a reasonable goal. But giving people specific timelines without the caveats that come with those studies does them a disservice, and it's worth unpacking what the evidence actually shows.

Does the science back this up?

On insulin, the evidence is actually fairly solid. Diet-driven insulin changes can happen fast, sometimes within 24 to 72 hours, particularly in people with insulin resistance who reduce refined carbohydrates or overall caloric load. A 2018 study by Lim et al. in Cell Metabolism showed meaningful improvements in insulin sensitivity in just days following dietary restriction. So "three days" is not fabricated. It is, however, a best-case scenario in a motivated population with an appropriate dietary shift.

The testosterone-carbohydrate claim is more specific and more contested. There is research connecting low-carbohydrate diets to reductions in free testosterone and SHBG in women with polycystic ovary syndrome (PCOS), a condition that often drives elevated androgens. A study by Marsh et al. (2010, American Journal of Clinical Nutrition) found hormonal changes in PCOS patients on a low-glycemic diet over 12 weeks, not seven days. The seven-day figure is harder to pin to a robust source. It may exist in a smaller pilot study, but presenting it without that context makes it sound more universal than it is.

On estrogen and progesterone taking four to six weeks: this is a reasonable rough estimate for cycle-linked changes, but it conflates a lot of different hormonal processes and ignores that these hormones fluctuate enormously within a single menstrual cycle.

What did they get wrong (or right)?

They got the insulin part broadly right. Fast insulin responses to dietary change are well-documented, and framing food as a lever is accurate. Credit where it is due.

Where it goes sideways is the testosterone claim. Saying "within seven days you can actually change your testosterone levels" through carbohydrate reduction sounds like a treatment protocol. For women with PCOS or clinically elevated androgens, dietary change is a real and studied intervention, but the seven-day timeline is not well-supported by large trials. Most of the meaningful research shows hormonal shifts in androgen levels happening over weeks to months, not days.

The estrogen and progesterone section is the weakest. Saying nutrients "drive" estrogen and progesterone balance in four to six weeks oversimplifies how these hormones work. Estrogen in premenopausal women fluctuates dramatically across a 28-day cycle regardless of diet. The relationship between nutrition and sex hormone production is real, particularly through body fat, insulin sensitivity, and liver metabolism, but the four-to-six-week framing implies a linearity that does not match physiology.

• Insulin: fast change with diet is accurate, timeline is roughly correct in responsive populations.
• Testosterone reduction in seven days via low-carb: plausible but overstated given the evidence base.
• Estrogen and progesterone in four to six weeks: too simplified and potentially misleading.

What should you actually know?

Hormones are not fixed settings you adjust like a thermostat. They exist in a dynamic, feedback-driven system where sex, age, body composition, stress, sleep, and underlying conditions all matter more than any single dietary change. The framing of "three days" and "seven days" is appealing because it feels actionable, but it sets people up for frustration when their own timeline does not match.

If you have elevated testosterone, irregular periods, or symptoms that suggest a hormonal issue, dietary change is worth exploring, particularly reducing refined carbohydrates and improving insulin sensitivity. But the existing evidence, including work by Azziz et al. on PCOS management and dietary interventions reviewed in Fertility and Sterility, consistently shows that meaningful hormonal improvements take weeks to months and are most meaningful in people with specific underlying conditions like PCOS or insulin resistance.

For people with clinically diagnosed hormone disorders, including hypogonadism or androgen excess, dietary changes are supportive, not curative. Anyone seeing a provider about testosterone or estrogen levels should treat these timelines as rough orientation, not a protocol.