The fast early drop: glycogen and water

Your body stores quick-access energy as glycogen, and glycogen holds onto water, roughly 3 grams of water for every gram of it.

When you start eating less or moving more, your body burns through glycogen first because it is the easiest fuel to reach. As it goes, the attached water leaves too. That is the fast early drop on the scale, sometimes 3 to 5 pounds in the first week or two. It is real progress, but it is not fat yet.

What this means for you: do not let a big first-week drop set the expectation for every week, and do not be discouraged when week two is slower. Both are completely normal.