Physical progress can also be determined by hydrostatic weighing, electrical impedance, or by using skin fold calipers. If the patient habitually consumes foods with excessive fat levels, such diet pills are certainly useful. The reason for this is that there is a certain uncertainty in possible plans of slimming among overweight persons. By influencing brain chemicals called noradrenaline and serotonin, sibutramine helps to make a person feel full. However, they work by short-circuiting the body's tendency to store fat in its tissues.