These measurements are important because as you metabolize fat and add lean body mass your weight may not change as much as you might think as your true body emerges from the state of obesity. This will be reflected in your clothes becoming looser, but it is helpful to have a more objective measurement.

The chest is measured at the nipple level or widest part; the waist is measured at the level of the belly-button or widest part; and the hips represents the widest part of the butt.