The active ingredient in medication such as Acomplia, Rimonabant works by blocking receptors that signal hunger. These receptors can be found not only in the brain, but also in the fat cells, the digestive system, the liver and the muscles.

Doctors prescribe Rimonabant products to those who have a body mass index (BMI) greater than 30, or those with a BMI above 27 plus additional risk factors such as increased risk of heart disease or type two diabetes.

Rimonabant targets the body systems that control appetite, weight, metabolism and energy use, and can also reduce nicotine cravings.

In clinical trials lasting a year, around 25% of subjects lost at least 10% of their body weight, while almost half lost more than 5% of their body weight.

Crucially, waist circumference, which is considered a critical measurement, dropped by between 6 and 7 centimeters.

However, there have been concerns expressed about the use of this drug in those with any type of psychiatric condition. In the UK there have been reports of 364 users experiencing psychiatric reactions, including 48 reports of depression, and 16 reports of suicidal thoughts.

In the US, the Food and Drug Administration (FDA) has voted to ban the drug because of an increased risk of suicide.