Luteal phase
Also called: second half of cycle, premenstrual phase, post-ovulation phase
The luteal phase is the second half of the menstrual cycle, from ovulation until the day before the next period. It typically lasts 12 to 14 days. Progesterone is the dominant hormone in this phase. It slows gut motility, increases water retention, raises body temperature slightly, and can flatten mood. Bloating, cravings and fatigue cluster here, not because of food but because of progesterone.
What happens in the luteal phase
After an egg is released from the ovary at ovulation, the empty follicle becomes a structure called the corpus luteum. The corpus luteum produces progesterone for around 12 to 14 days. Progesterone prepares the uterine lining for a possible pregnancy. If pregnancy does not happen, progesterone falls, the lining sheds as a period, and the cycle resets. The luteal phase is the predictable hormonal half of the cycle. The follicular phase (the first half) varies more between people and from month to month.
What changes in your body
- Bloating: progesterone slows gut motility, so more gas builds up and water sits in tissues longer.
- Constipation: same mechanism, gut transit slows by around 1 to 2 days on average.
- Cravings: small but real increase in appetite, often peaking in the last week.
- Body temperature: rises by about 0.3 to 0.5 degrees Celsius after ovulation. The basis for fertility tracking by basal body temperature.
- Sleep: progesterone is mildly sedating early in the phase but can fragment sleep in the last week.
- Mood: more variability, more sensitivity. Premenstrual syndrome (PMS) sits in the last 5 to 7 days for around 75 percent of women.
How long is normal
12 to 14 days is the typical range. A luteal phase shorter than 10 days, called a short luteal phase or luteal phase defect, can make conception harder because the uterine lining does not have time to mature. It is one of the things investigated when conception is taking longer than expected. A luteal phase longer than 16 days without a period usually means pregnancy or a hormonal disturbance worth investigating.
What helps the luteal-phase symptoms
- Track your cycle. Most people are surprised how predictable their luteal-phase patterns are once they have 2 or 3 months of data.
- Lower-sodium evenings in the last week of the phase. Reduces water bloat noticeably.
- More fibre and water across the phase to offset slower gut transit.
- Walk daily. Movement counters the gut slowdown and stabilises mood.
- Magnesium glycinate or citrate (300 to 400 mg) in the evenings. Evidence is modest but reliable for cramps and sleep.
- Caffeine and alcohol are felt more strongly in the luteal phase. Cutting back the last 7 days often helps mood and sleep more than expected.
Why this matters for gut tracking
Bloating, cramping or constipation that recurs in the luteal phase is often hormonally driven rather than triggered by food. Many women spend years cutting foods chasing a pattern that turns out to be cyclical. A 3-month cycle log alongside symptom tracking usually reveals the pattern, and then the relationship to food becomes clearer because hormones are no longer a hidden variable.
Common questions
- Why am I so bloated in the second half of my cycle?
- Progesterone, which dominates the luteal phase, slows gut motility and increases water retention at the same time. Both effects compound. Bloating peaks 3 to 5 days before the period and resolves within 1 to 2 days of bleeding starting. It is hormonal and predictable, not a food problem.
- Can I shorten my luteal phase?
- Not really. Luteal-phase length is biology, set by how long the corpus luteum produces progesterone. It is fairly fixed within an individual. The follicular phase is the variable half. If your cycles are short overall, it is usually a shorter follicular phase, not a shorter luteal.
- Is PMS the same as the luteal phase?
- Related but not identical. The luteal phase is a hormonal phase. PMS is the symptom cluster (mood changes, bloating, breast tenderness) that affects most women in the last 5 to 7 days of the luteal phase. Severe PMS that disrupts daily life crosses into PMDD (premenstrual dysphoric disorder) and is worth a GP conversation.
- Does the luteal phase change on hormonal contraception?
- Yes, dramatically. Most combined pills suppress ovulation, which means there is no true luteal phase. Symptoms become more uniform across the month. Progesterone-only methods (mini-pill, IUS, implant) keep some luteal-like effects but smooth them out. Cycle tracking on hormonal contraception measures bleeding patterns, not natural hormones.