It may sound too good to be true but scientists claim they have created a pill that will make you fit without having to exercise.
Researchers at Harvard Medical School have discovered a hormone found naturally in the muscles that triggers the calorie-burning benefits of exercise and believe it could be used as a weapon in the battle against obesity.
Levels of the hormone, irisin, increase in the body during exercise, boosting energy expenditure as well as controlling blood glucose levels.
The Harvard scientists believe the hormone could lead to treatments for obesity as well as diseases such as diabetes and cancer. They also said the drug would benefit patients who could be treated with exercise therapy but are too weak.
However, doctors have warned that this will not be the cue to cancel your gym membership as although the hormone can aid weight loss is does not improve muscle strength.
Irisin triggers the production of ‘good fat’ or ‘brown fat’, which burns off weight and improves glucose tolerance. This type of fat naturally disappears as we age and is replaced by ‘bad fat’ or ‘white fat’, which typically collects around the waist.
Experiments found irisin helps to convert ‘white fat’ to ‘brown fat’, thus increasing energy expenditure and improving resistance to obesity-linked diabetes.
The study, published online in the journal, Nature, found that irisin has “powerful effects” on adipose tissue – deposits of white fat that store excess calories.
When obese mice were injected with a modest amount of irisin over a short period, their glucose control improved and a small amount of weight was lost.
Lead researcher Professor Bruce Spiegelman says the weight loss results could improve with more extensive irisin treatments.
He said: "Whether longer treatments with irisin and/or higher doses would cause more weight loss remains to be determined.”
To compare the benefits of irisin with exercise, the drug was injected into sedentary mice that were obese and pre-diabetic.
Within 10 days of treatments the mice lost a small amount of weight and had improved control of blood sugar and insulin levels, which could prevent the onset of diabetes.
It is hoped the findings will help in understanding the biological mechanisms that convert physical exercise into beneficial changes in the body. However, Professor Spiegelman stresses that irisin supplements would not act as a 'miracle pill' to replace regular exercise.
“We’re not trying to replace diet and exercise. That is still important,” he added.
Because irisin is a natural substance and the mouse and human forms of the substance are identical, Professor Spiegelman believes it should be possible to begin clinical testing within two years, the Telegraph reports.
Richard Scrivenor, health, fitness and nutrition lecturer at Premier Training International, does not believe irisin is necessary in the fight against obesity.
He told The Huffington Post: "White fat or adipose did not just appear from nowhere one day in your life; it accumulated as a result of your internal physiology telling it to via hormone messengers promoting fat storage."
He added: "If we manipulate our physiology all day every day, promoting optimal internal health by eating, resting, sleeping and exercising, there would be no need to be considering irisin."
While a pill may one day offer help with shedding pounds, exercise offers a multitude of additional benefits, both emotionally and physically. See our gallery of the health benefits of running - more satisfying than swallowing a pill.