The seminar closes with a clear request: if hormones are your topic, get blood work done and have it interpreted by someone who knows the context. These markers are worth discussing with your doctor. In perimenopause single values fluctuate strongly, so from the age of 45 the diagnosis is usually based on symptoms and cycle changes .

Across a lifetime, their levels follow a curve rather than a straight line. A short surge right after birth, called mini-puberty , is followed by years of quiet, a steep rise in puberty and a long plateau. Then the paths split. In women, the menopause transition reshapes the hormone profile over several years . In men, testosterone tends to fall slowly and steadily .

Progesterone, cortisol, aldosterone, testosterone and estradiol share one origin. The first conversion, from cholesterol to pregnenolone, takes place inside the mitochondria; a small set of enzymes handles every step after that . The adrenal glands use the pathway to make cortisol, aldosterone and DHEA. The ovaries and testes use it to make progesterone, testosterone and estradiol.

Your liver builds most of the cholesterol you need from acetyl-CoA, which comes from carbohydrates, fat and protein. That makes cholesterol essential. It does not make it harmless: LDL cholesterol that stays high for years is a proven cause of atherosclerosis . For women this matters most after menopause. LDL rises noticeably within about a year of the final period , and cardiovascular disease is the leading cause of death in women .

You will often hear that cortisol “steals” the raw material of sex hormones. The observation behind it is correct: under chronic stress, sex hormones fall. The mechanism sits higher up. Stress signals slow the GnRH pulses in the hypothalamus, so the pituitary sends fewer LH and FSH signals, and ovaries and testes produce less . Open “The control loop” in the diagram above to see it.

Under-fuelling uses the same brake. When energy intake falls below roughly 30 kcal per kilogram of fat-free mass per day, LH pulses become disrupted within days . Restrictive dieting combined with a lot of exercise, common among teenage girls and young women worried about their weight, can stop ovulation altogether, with consequences for bone, fertility and mood. Men are affected too: low energy availability lowers testosterone . Chronic stress is also linked to more abdominal fat, particularly in women with a stronger cortisol response .

The supply is finite. A girl is born with around one to two million immature follicles. By puberty roughly 300,000 to 400,000 remain, and at menopause fewer than 1,000 are left . Each month a whole group starts to mature, while usually only one ovulates.

Timing is everything when testing. Progesterone is naturally close to zero in the first half of every cycle. A low value is only meaningful when it is measured about seven days before the next expected period, which is day 21 in a 28-day cycle . FSH, LH and estradiol are usually measured on days 2 to 5.

Your body replaces around 330 billion cells every day , and every new cell needs folate to copy its DNA. In pregnancy, demand rises sharply. Folic acid taken before conception substantially lowers the risk of neural tube defects such as spina bifida , , and it has been linked to a lower risk of cleft lip .

Vitamin D receptors are found in the ovary, the uterine lining and the placenta. In a meta-analysis, women with vitamin D deficiency (below 50 nmol/L) had nearly twice the odds of miscarriage compared with women with sufficient levels . In fertility treatment, women with sufficient vitamin D had higher live-birth rates . Whether supplementation prevents miscarriage has not been proven yet. Testing and correcting a deficiency before trying to conceive is still low-risk and sensible.

One caution: high doses of preformed vitamin A harm an unborn child. Before and during pregnancy, stay within the recommended amount .

Menopause is a single point in time: 12 months after the final period. The average age is around 51 in Europe and North America, with most women reaching it between 45 and 55 . The years before it, perimenopause, often begin in the mid-40s and can last from a few years to about a decade . Progesterone typically falls first, as more cycles pass without ovulation. Estradiol fluctuates, sometimes peaking higher than ever before it falls. FSH rises.

Hot flushes and night sweats affect most women and last a median of 7.4 years . Yet the transition reaches far beyond them, to bones, heart, muscle, sleep and the urogenital tract. Diet may play a role in timing: in a large UK cohort, more oily fish and legumes went with a later natural menopause, more refined pasta and rice with an earlier one .

Important: in perimenopause, periods can pause for months and come back. After 12 months without bleeding, however, any new bleeding needs to be checked by a doctor promptly .

Evidence: age at menopause ; hot flushes ; bone loss ; heart .

Current evidence supports that view. Menopausal hormone therapy (HRT) is the most effective treatment for hot flushes and night sweats, and it prevents bone loss. For healthy women under 60, or within 10 years of their final period, the benefits generally outweigh the risks . Risks depend on type, dose, route and duration: combined estrogen and progestogen therapy increases breast cancer risk modestly, more so with longer use , and estradiol applied through the skin carries a lower risk of blood clots than tablets .

Dosage matters in both directions. The European reference intake for vitamin D is 15 µg (600 IU) a day for adults ; the tolerable upper intake level is 100 µg (4,000 IU) a day . Higher repletion doses belong in a doctor’s hands, after a 25(OH)D blood test.

Protein is a hormone nutrient too. For healthy older adults, experts recommend 1.0 to 1.2 g of protein per kilogram of body weight a day, more with regular training . Eggs are among the most nutrient-dense foods there are: an egg holds almost everything needed to build a chick.

Evidence: magnesium and vitamin D ; vitamin K and vascular calcification ; adding folic acid to blood-pressure treatment reduced first strokes by 21 % in a large trial .

Eating the building blocks isn’t enough; the body needs a reason to use them. Working muscles release hundreds of signalling molecules, called myokines, that act on fat tissue, liver, bone, brain and the immune system . They are part of the biology behind the feeling after a good workout.

For midlife, two forms of training matter most. Strength: heavy, progressive resistance and impact training improved bone density and function in postmenopausal women with low bone mass, safely and under supervision . Base endurance: fat oxidation peaks at moderate intensity , in the zone where you can still talk in full sentences. The formula 208 − 0.7 × age estimates maximum heart rate more accurately than 220 − age .

Two myths are worth dropping. Training on an empty stomach does not lead to more fat loss over time ; if you feel flat in workouts, eat beforehand. And for fat loss, total energy balance and muscle preservation matter more than the “right” zone. Hard sessions are valuable as long as fuel and recovery keep up.

Evidence: WHO guidelines on physical activity .

Evidence: testosterone testing in men .