You ate normally, you trained, you slept — and the scale is 1.8 kg higher than yesterday. Before drawing any conclusion, do the arithmetic: gaining half a kilogram of body fat requires roughly a 3,500 calorie surplus. Two kilos of fat would take around 14,000. Nobody does that at dinner.
What moved was water.
The five things that move body water
| Cause | Typical swing | Clears in |
|---|---|---|
| High-salt meal | 0.5–1.5 kg | 1–3 days |
| High-carbohydrate day | 0.5–2 kg | 1–2 days |
| Hard or unfamiliar training | 0.5–1 kg | 2–4 days |
| Luteal phase of the cycle | 0.5–2 kg | Resolves after the period starts |
| Long flights, heat, alcohol | 0.5–1.5 kg | 1–3 days |
Each gram of stored carbohydrate holds roughly three grams of water with it, which is why a carb-heavy weekend shows up so dramatically and disappears just as fast.
Weigh in a way that tells the truth
Same time, after the toilet, before eating or drinking, similar clothing. Then look only at the weekly average. Daily readings are almost pure noise.
Training makes it worse before it makes it better
New or unusually hard sessions cause a small inflammatory response as muscle repairs, and that draws water into the tissue. It is common to see the scale rise in the first two weeks of a new programme while body measurements are unchanged or improving. This is one of the most reliable reasons people quit a plan that is working.
Wednesday in that week was a salty dinner out. Nothing about the plan changed, and the weekly average still fell.
What actually helps it settle
- Go back to your normal salt intake rather than cutting salt drastically, which tends to backfire.
- Keep drinking normally. Restricting fluid makes the body hold on to more, not less.
- Move. Walking helps circulation and reduces the pooling that shows up as puffy ankles.
- Sleep. Short sleep and high stress both push water retention up.
Kiva's reminder
If you tracked honestly and the day was normal, the number on the scale is information about water — not a verdict on your week.
When swelling is a medical matter
Sudden swelling in one leg, swelling with breathlessness or chest discomfort, facial swelling, or persistent puffiness that does not settle over days should be assessed by a doctor promptly. Certain medications and heart, kidney, liver or thyroid conditions cause fluid retention that needs medical management.
Frequently asked questions
Why did I gain two kilos overnight?
Almost certainly water and gut contents. Gaining half a kilo of body fat requires a surplus of roughly 3,500 calories, which is not achievable in a single evening for most people.
Does salt make you gain weight?
It increases the water your body holds, which shows on the scale, but it does not add fat. The effect usually resolves within a few days once intake returns to normal.
How do I reduce water retention?
Return to your usual salt intake, drink normally rather than restricting fluid, move, and sleep. Persistent swelling — especially in one leg, or with breathlessness — needs a doctor, not a home remedy.
Keep reading
The four phases of your cycle, explained simply
What actually changes across follicular, ovulation, luteal and menstruation — and how to plan food, training and rest around it.
Why weight loss stalls — and what to do
Almost every plateau is one of four things — and only one of them is physiology. How to find yours.