OTC diet pill Alli now on sale in the U.S.

The first and only over-the-counter (OTC) product for weight loss approved by the Food and Drug Administration (FDA) has gone on sale in the U.S.

The drug Orlistat, brand name Alli, works by blocking the absorption of one-quarter of any fat consumed and is an OTC version of Xenical, a prescription weight loss pill.

In a study into the use of Alli, mildly to moderately overweight individuals took either Alli or a placebo for a three month period and it was found that the drug enabled those on it to lose an additional two to three pounds for every five pounds lost through diet and exercise.

Manufacturer GlaxoSmithKline (GSK) does admit that Alli has some unpleasant gastrointestinal side effects, including gas, diarrhoea, leakages and oily discharges.

GSK is being careful about it's marketing approach and is emphasizing that people taking Alli also need to diet and exercise.

Experts say though the drug is expensive, many people believe the benefits outweigh the cost of the drug.

Many others though are discouraged when they don't lose as much weight as they hoped and go off the drug.