PMS symptoms: is weight gain normal?
Have you ever noticed you feel a bit heavier or more bloated just before your period starts? You're not imagining things. Research suggests that weight can fluctuate throughout the menstrual cycle, and it’s perfectly normal for the number on the scale to tick up slightly during the days leading up to your period.
One study from 2023 found that women gained around 0.5kg during parts of their menstrual cycle compared to their first week. This shift is thought to be linked to increased fluid retention. But don’t worry—this isn’t permanent weight gain, and it usually disappears naturally during the first few days of your period.
Common PMS symptoms
Premenstrual syndrome (PMS) refers to the collection of symptoms many people experience in the week or so before their period. These symptoms can come and go or vary month to month, but PMS is a common experience for many.
Some common PMS symptoms include:
- Mood swings
- Irritability
- Food cravings
- Acne
- Breast tenderness
- Bloating
- Weight gain
Why can PMS cause weight gain?
While everyone’s experience is different, temporary weight gain before your period is common. Several biological changes drive this shift, all tied to the natural hormonal fluctuations your body goes through each cycle.
Hormonal changes
In the days leading up to menstruation, oestrogen levels fall and progesterone levels rise. These shifts can trigger fluid retention, which may show up on the scale or make you feel puffier in certain parts of your body. Importantly, this is water weight—not fat.
Period cravings
Craving sugary or salty foods during your period? Progesterone and metabolic changes can make you more inclined to reach for comfort food. But indulging in these cravings can lead to more water retention, especially if the foods are high in salt or simple carbs.
Menstrual bloating
That tight, swollen feeling in your stomach before your period can also contribute to weight fluctuations. Hormonal changes can lead to gas buildup in the gastrointestinal tract, adding to that bloated sensation.
Constipation
As progesterone peaks before menstruation, digestion can slow down. This slowdown often brings constipation, which can leave you feeling heavier. One study in Japan found changes in regularity tied closely to menstruation, with nearly 20% of those affected experiencing constipation during this time.
Tips to help reduce period weight gain
There’s no guaranteed way to avoid period-related weight gain altogether, but a few lifestyle habits may help ease bloating and water retention. Keeping these practices up regularly—not just during your period—can support more consistent comfort.
Staying hydrated
It might sound odd, but drinking more water can actually help your body avoid holding onto extra fluid. When you’re dehydrated, your body tends to retain water to compensate. Aim for about six to eight glasses a day to stay well-hydrated.
Eat a balanced diet
Eating plenty of fiber-rich, whole foods can help digestion run more smoothly throughout the month. Probiotics may also support gut bacteria and ease bloating and constipation. Some limited studies even suggest a link between probiotics and hormone balance, although more research is needed.
Exercise
Though working out might be the last thing you feel like doing while cramping, movement can help your body release water through sweat. Even a gentle yoga session or a walk can make a difference. Physical activity may also help counter the digestive slowdown that can come with hormone shifts.
Supplements
Some studies suggest that magnesium and vitamin B6 might help ease PMS symptoms like cravings and fatigue. While the evidence isn’t overwhelming yet, both nutrients are known to help reduce tiredness. Trials have also shown magnesium’s potential to support digestion and relieve constipation, though its specific effects on PMS-related bloating need further study.
When weight gain might not be a normal PMS symptom
If your weight gain is ongoing and paired with irregular periods, there may be an underlying health issue involved, such as polycystic ovary syndrome (PCOS). This condition involves higher levels of androgens like testosterone, which can lead to weight gain.
PCOS also affects how the body responds to insulin, making it harder to process carbs effectively and can cause the body to produce more insulin, contributing further to weight increases.
The final say
Weight gain during PMS is usually temporary and nothing to stress about. Staying hydrated, eating well, exercising regularly, and supplementing with magnesium or vitamin B6 could help ease some of the bloating and other PMS discomforts.
If you suspect your symptoms may point to something more persistent like PCOS, it's a good idea to consult your GP for guidance.