adipex helps to promote weight loss by decreasing appetite or increasing the feeling of being full. It works Immediately like a catalyst which increases the weight loss process. Adipex diet pill makes you feel less hungry by increasing one or more brain chemicals that affect mood and appetite. phentramin d decreases appetite by possible changing brain levels of serotonin. Phentermine is a nervous system stimulator like the amphetamines, causing suasion, elevation of blood pressure, and faster heart rate.