About 6 in 10 people get bloated before their period, and it's usually water and gas. Fat has nothing to do with it. Yes, it's annoying when your favourite jeans suddenly feel tight. Your body holds the most water on the first day of your period and the least about a week after it starts.
Is it real weight gain?
No. In a study of 42 women, weight went up by about half a kilo on average during their period, and almost all of that was water. Some people see bigger swings, so it's easier to put the scales away from the week before your period until it ends.
Why does my belly swell?
Two different things are going on. Water retention feels like puffiness: rings and shoes get tighter. Gas in your gut stretches your belly from the inside.
Researchers still don't fully know why it happens right before a period: hormone levels in blood tests don't match up neatly with the swelling. On top of that, about 1 in 7 people get constipated before their period, and that can make your belly feel swollen too.
What helps the bloating go down?
Cut back on salt and fizzy drinks. Eat slowly, in smaller portions and with your mouth closed so you don't swallow air. If cabbage, beans or lentils make you gassy, have less of them on these days.
Moving helps: a walk or any light activity gets your digestion going. If gas is pushing your belly out, massage your tummy, moving your hand from right to left. If you're constipated, add oats or linseed, and increase fibre gradually.
And keep a couple of looser things with a soft waistband for these days. When nothing digs in, a swollen belly bothers you a lot less.
Common questions
Should I drink less water so I don't swell?
No, the opposite: the NHS recommends drinking plenty of water when you're bloated, and when you're constipated too.
Do water pills or diuretic teas help?
Don't take them on your own. If the swelling is really bad, a doctor can prescribe a diuretic. Combined with ibuprofen, diuretics can harm your kidneys.
Is there a pill for bloating?
A pharmacist can suggest simeticone, which eases bloating, or a laxative if you're constipated. ACOG says magnesium may reduce water retention with PMS, but talk to a doctor before you start it.
In short
- Put the scales away until your period ends
- Swap fizzy drinks for plain water
- Go for a walk when you feel bloated
Source: NHS: Bloating
Educational content; it does not replace professional medical advice.