A drug which treats obesity by reducing the desire to eat has been launched in the UK, but the Fitness Industry Association (FIA) has warned that being active is still the most effective way to lose weight.

Rimonabant is the first drug to target factors governing the body’s appetite, metabolism and energy use and trials showed it can reduce body weight by a tenth.

However, experts stress that the pill cannot replace the need for healthy living.

Gill Morgan, chief executive of the NHS Confederation, said weight loss is “predominantly about diet and exercise”, an opinion echoed by the FIA: “The new wonder pill addresses the symptoms, not the cause, of obesity,’ said a spokesperson.

“The only true long-term solution to the problem is an intervention strategy, which changes the behaviour and lifestyle of sufferers, addressing both dietary and activity issues.

“The most effective and the cost-efficient solution to Britain's obesity problem lies not in pharmacology or surgery, but in educating and motivating consumers to be conscious about what they consume and to be more active, more often.”

Rimonabant will be assessed by the National Institute for Health and Clinical Excellence (NICE). At a cost of over £55 for a month’s treatment it could, if approved for widespread use, cost the NHS billions of pounds.