Does your weight change with your menstrual cycle?

Short answer

It changes, but only a little. Weight rose about 0.5 kg during the period, and the extra was water outside the cells. Fat stayed the same; the bigger shift across the cycle was eating 168 kcal more a day after ovulation.

Does your weight change with your menstrual cycle?
'Around your period → bloating → the scale goes up' — is that right?
When the scale climbs around your period, it is easy to feel your diet has failed. We checked how much weight really changes and whether the extra is fat or water.
It does change, by about 0.5 kg
Weight was highest during the period
Researchers measured weight and body composition in 42 women 2 times a week across one cycle. Weight during the period was 0.45 kg higher than in the first week of the cycle. Water outside the cells rose 0.474 kg at the same time, so most of the gain was water.
Fat did not go up
Body fat percentage and muscle stayed the same
In the 42-woman study, nothing else in body composition changed. When 21 women were measured early in the period and about a week after ovulation, weight went from 65.2 kg to 64.9 kg, a 0.3 kg difference, while body fat percentage and lean mass (muscle and everything except fat) did not differ. The researchers put the change down to shifting body water.
Across the whole cycle, the change stayed small
Four weigh-ins moved within 0.4 kg
When 36 women were measured during the period, before ovulation, at ovulation and just before the next period, weight and body fat did not differ between phases. Average weight moved within 0.4 kg both in women on the pill and in women off it. A study that measured 52 women three times also found no phase differences in weight, body fat or body water.
Feeling bloated was bigger than the weight change
The most bloated-feeling day was the first day of the period
When 62 women rated bloating every day for 1 year, across 765 cycles, it peaked on the first day of the period. In 39 women who felt more bloated during the period than before ovulation, body fat percentage and estimated body water did not differ between the two times.
What changed with the cycle was how much people ate
After ovulation, they ate 168 kcal more a day
An analysis that pooled 15 data sets with 330 women found they ate 168 kcal more per day on average from ovulation until the period. That is about half a bowl of rice. Calories burned at rest were only slightly higher in this phase, in an analysis that pooled 26 studies with 318 women.
Bottom line: the 0.5 kg during your period is water
Compare weigh-ins from the same phase
Around the period, weight rises about 0.5 kg, and the extra is water outside the cells. Fat and muscle stay the same. In a 30-woman study, the size of the change varied a lot from person to person, so during a diet you can compare weights from the same phase of the cycle. The part worth watching is the extra 168 kcal a day after ovulation.