Appetite suppressants are used to decrease appetite or increase the feeling of being full in overweight patients by possibly increasing levels of serotonin or catecholamine what're brain chemicals that effect mood and appetite. Because the brain plays an essential role in the control of appetite, researchers have looked at various neurotransmitters, specifically serotonin, dopamine and nor-epinephrine.

This class of weight control drugs act on the central nervous system (CNS) to suppress appetite.  

Appetite suppressants generally modulate neurotransmitter function in the central nervous system are known to act by increasing the availability of catecholamines, in particular noradrenaline, in certain areas of the brain, hence resulting in perceived suppression of hunger or reduced appetite. By suppressing appetite, less food is eaten, and caloric intake is lowered.

However, reducing appetite pharmacologically has a number of drawbacks, including a decrease in the weight loss efficacy of the medication over a period of time.

Side Effects

Drugs that affect neurotransmitters also affect the central nervous systems and thus may result in jitteriness and anxiety. In addition, these appetite suppressing agents can produce cardiovascular effects that may have very serious consequences.