Why nutrition needs change across the cycle

The hormonal changes across the menstrual cycle produce real, measurable shifts in metabolism. Insulin sensitivity — the body's ability to use carbohydrates efficiently — is significantly higher in the follicular phase than in the luteal phase. Progesterone in the luteal phase raises basal metabolic rate by 200 to 300 calories per day and directly increases appetite. Oestrogen influences protein metabolism and supports muscle protein synthesis. Iron levels drop with menstruation.

Eating the same diet every day of the month ignores all of this. It is not that any particular food is "wrong" in a given phase — it is that the body uses macronutrients differently depending on the hormonal environment. Adjusting food choices and quantities to match that environment is not restriction. It is precision.

Should women eat differently throughout their menstrual cycle?
Yes — the research is clear that insulin sensitivity, metabolic rate, appetite and protein utilisation all vary measurably across the four hormonal phases. Adjusting nutrition to these changes — eating more carbohydrates when insulin sensitivity is high in the follicular phase, eating more overall when metabolic rate is elevated in the luteal phase — improves energy, body composition and hormonal health outcomes.

Phase-by-phase nutrition — what to eat and why

Menstrual phase (Days 1 to 5) — replenish and support.

Iron-rich foods are the priority: red meat, dark leafy greens, lentils, pumpkin seeds. Blood loss depletes iron stores and low ferritin is one of the most common causes of persistent fatigue in women of reproductive age. Vitamin C alongside iron-rich foods significantly improves absorption. Magnesium-rich foods — dark chocolate, leafy greens, avocado — support cramping reduction. Warm, anti-inflammatory meals — ginger, turmeric, salmon — help manage prostaglandin activity, the primary driver of period pain.

Follicular phase (Days 6 to 13) — fuel the energy.

Insulin sensitivity is at its highest. Carbohydrate tolerance is better than at any other phase — the body uses them efficiently for energy and training. Lean protein to support the muscle building that oestrogen facilitates. Cruciferous vegetables — broccoli, cauliflower, Brussels sprouts — support oestrogen metabolism through a compound called DIM (diindolylmethane), which helps the liver process and clear oestrogen efficiently. Fermented foods for gut health, which directly affects oestrogen metabolism.

Ovulatory phase (Days 14 to 16) — light and anti-inflammatory.

The shortest phase — eat lightly and cleanly. Zinc-rich foods — pumpkin seeds, beef, shellfish — support ovulation and testosterone balance. Antioxidant-rich vegetables and fruits protect against the inflammatory response that ovulation itself triggers. Adequate hydration is important as oestrogen peak and the LH surge both affect fluid balance.

Luteal phase (Days 17 to 28) — satisfy and stabilise.

Progesterone raises metabolic rate by 200 to 300 calories. Eating more is appropriate, not indulgent. Complex carbohydrates — oats, sweet potato, quinoa, brown rice — support serotonin production through the tryptophan pathway, directly addressing the mood and energy impact of declining oestrogen. Magnesium-rich foods throughout the luteal phase support GABA activity, cramping prevention and sleep quality. Reduce caffeine — it amplifies cortisol sensitivity that is already elevated. Reduce alcohol — it disrupts sleep architecture and worsens premenstrual symptoms.

What should women eat before their period?
In the week before your period (late luteal phase): complex carbohydrates to support serotonin and stabilise blood sugar, magnesium-rich foods (dark chocolate, leafy greens, pumpkin seeds) for mood and sleep, adequate protein for satiety, and anti-inflammatory foods (salmon, ginger, turmeric). Reduce caffeine and alcohol, which both worsen premenstrual symptoms. Eating more overall is appropriate — progesterone raises metabolic rate by 200 to 300 calories.
The increased appetite before your period is not a lack of willpower. It is progesterone raising your metabolic rate. Eating more is the physiologically correct response.

Key supplements to support cycle nutrition

Magnesium glycinate 375mg daily in the luteal phase — the most impactful single supplement for hormonal health, supporting mood, sleep, cramping and GABA receptor function as progesterone drops.

Vitamin B complex daily — B6 supports serotonin synthesis, B1 reduces prostaglandin activity and period pain, B12 supports energy throughout the cycle.

Iron after menstruation if you experience heavy periods. Ferritin testing is worth pursuing if you have persistent fatigue — low ferritin is extremely common and frequently missed.

Omega-3 fatty acids daily — reduces prostaglandin-driven inflammation, supports brain health through the hormonal transitions and reduces the severity of period cramps.

What are the best supplements for women's hormonal health?
Magnesium glycinate 375mg daily in the luteal phase (mood, sleep, cramping). Vitamin B complex daily (serotonin, energy, period pain). Iron post-menstruation for women with heavy periods. Omega-3 fatty acids daily (inflammation, brain health). These address the specific nutritional gaps created by the hormonal cycle rather than general wellness supplementation.