Your body is composed of mostly water (over 90%). The scale measures everything, fat, muscle, tissue, bone, water, etc. Fat, muscle and water can all fluctuate meaning you can lose fat without changing weight and you can gain water while maintaining muscle/fat. In my weight loss journey, I've had lots of ups and downs despite being on plan (and some ups/downs while not being on plan

). It all evens out over time. A single week is really not a good time period to judge your weight loss by.