My weight hasn't moved in two weeks. Has my diet stopped working?

Why the scale lies in the short term

Your weight on any given morning is fat, muscle, water, stored carbohydrate (glycogen), and whatever is in your gut. Fat changes slowly. The others swing daily:

• Glycogen carries water. A higher-carb day can add a kilogram or more overnight. A low-carb day takes it off. Neither is fat.
• Salt, alcohol, a big restaurant meal, poor sleep and a hard leg session all cause temporary water retention.
• The food itself has weight. More fibre and more volume means more in your gut at the morning weigh-in.

On a moderate deficit, real fat loss might be 0.3–0.5 kg a week. Daily water swings are often bigger than that, which is why a single weigh-in tells you almost nothing.

The menstrual cycle adds a predictable swing

Weight was about 0.45 kg higher during menstruation than in the first week of the cycle, and almost all of that was extracellular water. No change in fat. That is the average: some women swing much more, some barely at all. Either way, comparing week 1 of one cycle to week 3 of another is comparing noise.

Does weighing often help or hurt?

Weight-loss programmes that included self-weighing beat minimal interventions, and daily versus weekly weighing made no difference. Weighing on its own, with nothing else, had no evidence behind it. The scale is a measuring tool, not a strategy.

When to actually adjust

My rule with clients: three weeks of a flat weekly average, with honest tracking, before anything changes. Then make one small change: about 100–200 kcal a day less, or 2,000–3,000 more daily steps. Not both, and not a crash.

Before cutting food, check the usual leaks: weekends, cooking oil, drinks, "bites" while cooking, and portions that have quietly grown. A stall that turns out to be tracking drift is far more common than a metabolism that has stopped.