What happens in the second half of the cycle
After ovulation, the luteal phase begins. Progesterone rises and shapes the second half of the cycle until, shortly before the period, both hormones fall again. This phase brings the symptoms many know as premenstrual syndrome: tension, bloating, breast tenderness, mood swings – and a change in body weight.
During this time the body holds on to more water. On the scales, that looks like weight gain. Your body fat hasn't changed that week; that would take a considerable energy surplus, which a few days simply can't produce.
Why it costs more than a kilo
The real problem isn't the water but the interpretation. If you take the number as a verdict on your training, you draw the wrong conclusions in exactly that week: calories get cut, training gets harder, or the plan is dropped altogether.
Measuring more sensibly
- Compare cycle with cycle, not week with week. Always use the same point in the cycle – say, the third day after your period starts. Only then are you comparing like with like.
- Leave the scales alone in the week before your period. They give no useful information then, but they cost motivation.
- Use several measures. Strength, measurements, sleep and energy together give a more reliable picture than a single number.
- Look over months, not days. Body composition changes slowly. A trend over three cycles says something; a swing over three days doesn't.
What Rhythmus does with this
The app brings your entries together across cycles instead of setting daily values against each other. The daily energy check-in is deliberately not a weight field: how you feel steers training – not what the scales show on a single morning.