Herbal diet pills tend not to make a massive difference to how much weight you can lose, but rather help you by providing that little bit of extra psychological motivation and taking the edge off your appetite. If you are going to buy these types of diet pills, make sure that you read the label carefully and that you are fully aware of the listed side effects and ingredients. Never take more than the recommended dose. Be aware that there are many that make unfounded claims too, because the herbal diet pill market place isn't regulated, so do make sure that you research exactly what you're buying to avoid disappointment. Remember, if it sounds too good to be true, then it probably is. OTC Diet pills with 'Natural', 'Herbal' or similar descriptions are not necessarily any healthier than other diet or weight loss pills. Herbal supplements are often labeled "all natural" and are considered by the FDA to be food products as opposed to drugs. In fact, some of these herbal diet pills are associated with some major health concerns. So do not trust diet pills just because they sound 'natural'.

The second type, is of course, the synthetic diet pills. Products considered by FDA to be over-the-counter weight control drugs [as opposed to dietary supplements] are primarily those containing the active ingredient phenylpropanolamine (PPA). In 2000, the FDA requested that drug manufacturers voluntary reformulate PPA-containing products in the wake of evidence that phenylpropanolamine can increase the risk of stroke, so there are few diet drugs on the market that still contain this ingredient.

Prescription drugs such as Meridia and Xenical are only available with a doctor's prescription. They are carefully regulated by the Food and Drug Administration (FDA) Center for Drug Evaluation and Research, and their use is closely monitored by the prescribing doctor.