Why does the scale go up on days I under-eat?

On Ep. 135 of The WarriorBabe Show, Nikkiey frames it this way: your body is always trying to maintain its internal balance, and a low-intake day can make it feel like it's working against you. She points to water retention first. Under-eating can stress your body and potentially raise cortisol, and she says elevated cortisol makes your body retain more water. That's especially likely if you were very active the day before and then didn't eat enough to match it.

The second piece is what she calls metabolic adaptation. When you under-eat, Nikkiey says your body shifts into conserving energy. It slows how it processes food and beverages so it can hold on to them and use them when it needs to. Slower processing plus extra water is why the scale can spike on the exact day you thought you were being good.

The takeaway: a higher number after a low-food day is your body reacting to stress and scarcity, not a sign you need to cut harder. Eating less to fix a spike can feed the very stress that caused it. A steady plan that fuels your activity gives you a scale you can actually read.