The fast first week is mostly water
The rapid drop many people see in the first week of a diet is encouraging but largely not fat. Cutting calories, and especially cutting carbohydrates, depletes stored glycogen, and each gram of glycogen holds several grams of water. As glycogen falls, that bound water is released, producing a quick scale decline of a few pounds that says little about fat lost.
Understanding this prevents two mistakes: overestimating early fat loss, and panicking later when the rate slows to its true pace.
Steady loss and the adaptive zone
After the initial water shift, weight settles into a steadier phase where the scale reflects genuine fat loss at a pace governed by the calorie deficit. Over the following weeks this is where the real composition change happens. Eventually many dieters reach a slower zone where metabolic adaptation, rising hunger, and reduced unconscious movement narrow the effective deficit, so loss decelerates even when effort holds.
The week ranges shown are illustrative averages; actual timing varies with deficit size, starting weight, and adherence. This is general educational information, not medical advice; consult a qualified professional for individualized guidance.