What is the Best Diet Pill?

There are quite a few diet pills that make weight loss claims, but only a few that work. And finding accurate information can be difficult because of all the website owners who stand to make a buck in commission by pushing a particular product. So the question remains: what are the best diet pills? These supplements work in one of three ways: by increasing metabolism, but suppressing the appetite, or by slowing absorption of calories. They vary in effectiveness at these tasks, and they vary greatly in safety as well. None of them are magic pills that will make fat melt away without having to change your lifestyle. Evolution has been too effective at getting your body to store fat.

Alli (Orlistat, Xenical)

This is an over-the-counter diet pill that works by suppressing an enzyme in the body that is involved in the absorption of fat. It actually has a moderate effect, in controlled studies it was found to cause a weight loss of 5 pounds more than those not using it. The main side effect is greasy loose stool, which can subside with time. Also, the FDA is currently investigating reports of rare liver damage seen in some using this medication.


The prescription-only drug Metformin is used primarily by diabetics to control their metabolism. It is effective at lowering the symptoms of type II diabetes and helps those patients lose a small amount of weight, and it has very few side effects. However, it is only by prescription and probably not ideal for non-diabetics.


A plant from South Africa, hoodia has long been known as an appetite suppressant. In the late 90s, Pfizer tried to synthesize the active chemical, called P57, in order to use it as a weight loss supplement. They later realized that it was extremely difficult to synthesize, without also having undesirable side products, which may cause liver problems. A research study involving rodents on hoodia's effectiveness demonstrated that quite a bit is required for any effect, and it is doubtful that supplement manufacturers put enough into their pills.


A stimulant, this was one of the most popular weight loss drugs available until it was banned in the US by the FDA in 2004. This was one of the more effective weight loss drugs, and was present in many branded supplements, such as Ripped Fuel. However, there is strong evidence that it can cause heart attacks and strokes and even death, and so it is no longer available. Most supplement manufacturers replaced it with less effective ingredients, such as bitter orange.

Green Tea

Green tea acts as a stimulant and also can increase metabolism safely, without increasing blood pressure or heartbeat. The effect is very small, however, and evidence for any moderate weight loss is slim. However, the supplement is most likely safe to take.

So where does that leave us?

None of the medications examined so far are ideal, so what is the best diet pill? The best over-the-counter one is probably Alli (Orlistat, Xenical), although with the caveat that rare liver damage has been seen in some users, and is currently under investigation by the FDA. This pill is moderately effective, and produces few side effects.

The best prescription pill is Metformin, although this is geared more towards diabetics and may not be all that effective for just normal weight loss goals.

Other than that, there are thousands of brands of supplements that use various combinations of herbal supplements, such as the aforementioned hoodia and bitter orange. You'll have to look at the ingredients to know exactly what's in them. There is no evidence that any of these are effective, and some, such as bitter orange, have some of the same serious side effects as ephedra. It is recommended to stay away from.