I was very interested to read how we lose weight. How many of us weigh each day (me ☺️) or are disappointed when we have a great week, but the scales do not reflect it? Now I know why. As fat is lost from fat cells, it is replaced with water. It can take days or weeks to lose this water. A sudden weight loss can relate to fat loss some time ago when you suddenly lose the water.
100down.org/the-whoosh-effect/
It also says that if you have a period of static weight, a cheat meal may help. This is just upping your calories. I have heard about this from a nutritionalist before. If on low carb eating; you up the carbs for a day. It seems odd, but that is what is said to work.
This is based on a war time experiment were men were on a semi- starvation diet (1500 cals). It is a very interesting read and will make me more complacent if the scales are not showing what I expect.