PMS Symptoms: Why the Week Before Your Period Feels So Different

By Tina Chagoury, Clinical Dietitian · 7 min read · 2026-09-27

For a few days every month you feel like a different person. Here is what your hormones are doing in the week before your period, and what makes it easier.

For a few days every month you become someone slightly different. Hungrier. Sharper with the people you love. Tearful for no clear reason. Bloated, puffy, jeans tight, skin breaking out. Then your period arrives and within a day or two it lifts. You are not imagining it, and you are not weak. Here is what is happening, and what makes PMS symptoms genuinely easier.

What happens in the week before your period

Your cycle has two halves. In the first, oestrogen rises and leads up to ovulation. After ovulation, in what is called the luteal phase, progesterone rises too. Then, if there is no pregnancy, both oestrogen and progesterone fall in the days before your period.

Here is the part most women are never told. In most women with PMS, hormone levels are normal. The difference is how sensitive the brain and body are to those normal rises and falls. That is why two women with identical blood results can have completely different weeks, and why PMS is not diagnosed with a blood test.

Oestrogen interacts with serotonin, one of the brain's mood messengers. Progesterone and its breakdown products act on the calming side of the nervous system. When both drop, some women feel the ground shift under them.

The symptoms, and when they appear

PMS symptoms appear in the second half of the cycle, typically in the week or two before bleeding, and ease within a few days of your period starting. The timing is what defines it.

Physical: bloating, fluid retention, breast tenderness, headaches, tiredness, acne, changes in bowel habit, disturbed sleep and strong food cravings.

Emotional: irritability, anxiety, low mood, tearfulness, feeling overwhelmed, and a shorter fuse than usual.

The bloating and bowel changes have their own mechanism, which I explain in why you bloat and sometimes get diarrhoea before your period.

Why the cravings are real

The cravings are not a lack of discipline. In the luteal phase your energy needs rise slightly, so you genuinely are a little hungrier. For many women, blood sugar also feels less steady in these days. When glucose dips, irritability and the pull toward something sweet rise together.

So feed the hunger well instead of fighting it with nothing:

• Protein at every meal, and a little more of it than usual.
• Carbohydrate with fibre, such as oats, lentils, sweet potato or whole grain bread, rather than refined sugar on its own.
• Regular meals, and no skipped breakfast. A skipped meal in this week is an almost guaranteed afternoon crash.
• If you want something sweet, have it after a meal, never on an empty stomach.

My guide to stopping afternoon sugar cravings goes deeper into the pattern.

Mood is physiology, not personality

Mood changes before a period are among the most dismissed symptoms women have. They are real, they have a mechanism, and they deserve to be taken seriously. I wrote about that in why "it is just her hormones" dismisses something real.

What helps the brain through this week is mostly unglamorous: steady blood sugar, protected sleep, daylight, movement, and fewer demands where you can arrange it.

Period pain

Cramps come from prostaglandins, substances released by the lining of the womb that make it contract. Some pain is common. What helps:

• Heat on the lower abdomen.
• Gentle movement, especially walking, rather than lying still all day.
• An anti inflammatory way of eating across the whole month: oily fish, vegetables, olive oil, fewer ultra processed foods.
• Pain relief as advised by your doctor or pharmacist.

Pain that stops you working, studying or getting out of bed is common, and it is still not something to accept. More on that below.

What actually helps PMS

• Steady blood sugar, as above. This is usually the change women feel first.
• Magnesium. It supports muscle relaxation and the calming side of the nervous system, and many women find it helps both mood and cramps. Food comes first: leafy greens, nuts, seeds, pulses. If you use a supplement the form matters, so read what to know about magnesium, and check with your doctor if you have kidney problems or take regular medication.
• Calcium from food. Dairy, sesame and tahini, sardines with their bones. Some evidence suggests adequate calcium may ease PMS.
• Sleep. Poor sleep amplifies every symptom on the list. Protect it most in this week.
• Less alcohol. It disturbs sleep, unsettles blood sugar and worsens mood the next day.
• Less caffeine if it makes you anxious or your breasts tender. Not everyone needs to cut it, so notice your own response.
• Less processed salt if bloating and puffiness are your main complaint.
• Regular movement through the whole month, not only on the good days.
• Track your cycle for two or three months. Note each symptom and the day it appears. This is the most useful thing you can bring to a doctor, and it shows you your own pattern.

These foundations, held across the whole month and not only the week before, are the core of the Hormone Reset Method™.

When it is more than PMS

PMDD. Premenstrual dysphoric disorder is a severe form in which mood symptoms, depression, hopelessness, rage or anxiety, are strong enough to damage your work or relationships every cycle. It is a recognised medical condition with effective treatments, and it needs a doctor. If you ever have thoughts of harming yourself, seek help the same day.

Endometriosis. Tissue similar to the womb lining grows outside the womb. Suspect it if your period pain is severe, if you have pain during sex or when opening your bowels, pain outside your period, very heavy bleeding, or difficulty conceiving. See a gynaecologist.

Something else. If your symptoms do not ease once your period starts, it may not be PMS at all. Low mood all month, thyroid problems or iron deficiency can look similar.

Perimenopause. PMS often gets worse in your forties, because progesterone falls earlier than oestrogen. That is common, and worth understanding rather than simply enduring.

This article is nutrition education, not medical advice. Severe pain, heavy bleeding or severe mood symptoms need assessment by your doctor.

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About the author. Tina Chagoury is a licensed clinical dietitian specialising in women's hormonal health, inflammation and gut health, and the creator of the Hormone Reset Method™. Learn more about the Hormone Reset Method.

Frequently asked questions

What are PMS symptoms a week before a period?

Bloating, breast tenderness, cravings, tiredness, headaches, acne, irritability, anxiety and low mood are the most common. They ease within a few days of your period starting.

Why do I crave sugar before my period?

Your energy needs rise slightly in the second half of the cycle, and blood sugar feels less steady for many women. Eat more protein, pair carbohydrate with fibre and do not skip meals.

How can I ease period pain naturally?

Heat, gentle movement, anti inflammatory food across the month and good sleep all help. Pain that stops normal life needs a doctor.

Does magnesium help PMS?

Many women find it helps mood and cramps. Start with food sources, and if you supplement, choose the form carefully and check with your doctor if you have kidney problems.

Is it PMS or PMDD?

PMDD is the severe form, with mood symptoms strong enough to disrupt work or relationships every cycle. It needs a doctor, and it is treatable.

Related reading

• Your Hormones Are Repaired at Night. That Is Why Sleep Comes First.
• What an anti inflammatory diet actually means in practice
• “I Don’t Feel Like Myself Anymore”: The Perimenopause Symptom Nobody Names