Why does my scale weight fluctuate?
Daily scale weight is noisy. Food volume, fluid, sodium, glycogen, bowel contents, menstrual cycle, demanding training, inflammation, travel, sleep disruption, and stress can all move the number independent of fat gain or loss.
Use trends, not single weigh-ins. Weigh under consistent conditions, compare weekly averages, and interpret changes alongside adherence, measurements, photos, training performance, and how clothes fit. A one-day jump after a salty, higher-carb meal is usually water and food mass, not a sudden body-fat increase.