Remember that throughout the day there are two factors that heavily influence weighing more in the afternoon: gravity and hydration. Gravity, during the course of a day, compresses your physical being downward; consequently, all fluids within in the body find a location in your organs, tissues, or cells and wait there until the body is at complete and extended rest (take sleeping as an example). Since all of the fluid is retained in various organs, tissues, and cells, the fluids will make you weigh more. The second factor is hydration. The body is better hydrated in the afternoon than upon waking up, because water is lost during sleep via breathing, which results in dehydration. When the body is dehydrated, the cells and tissues shrink. So, even abstaining from eating will have no effect on weighing more in the afternoon, because gravity and hydration largely determine what numbers are produced on the scale. I hope you found this answer thoughtful and beneficial.