He has a point. It is true, I have noticed this effect too. When training intense for around 3 hours a day you hold more water due to the physical stress on the body. When something happens and you can't work out for 2 or maybe even more days you will lose this extra fluids and then some. Especially if doing lot's of intense long duration (1+ hour) cardio, like running in the morning and then weights in the evening the body can hold a little more water. Also while not working out the body can devote all resources to repairing muscles and restoring energy and you will look and feel different. I work out almost every day of the year so I know this.