Review of the “Fitness Pill” AICAR & GW1516 currently in development.
Scientists are moving closer to developing a pill which could deliver some of the benefits of exercise – even for those who do not move a muscle. They have found the drug boosts fat burning and stamina in inactive mice.
The journal Cell reports US researchers now have two possible pills which appear able to build muscle, increase stamina and even burn fat. In tests, mice were able to run 44% further – suggesting humans may be able to do the same without prior training.
The drugs may even eventually help tackle muscle wasting diseases, or help improve the health benefits of exercise in people at risk of conditions such as diabetes.
The two drugs, labelled AICAR and GW1516, appear to have an effect on a gene involved in the building and regulation of muscle.
This “master gene” – PPAR-delta – has the ability to control the activity of many other genes – so adjusting it could in theory have a widespread effect on the way the body works.
Genetically altering mice to enhance the activity of the gene led to the development of muscle which was much more likely to burn fat than burn sugar.
It also made “marathon mice” who were able to run much further on a treadmill. The next step was to produce similar effects using a drug rather than a genetic alteration.
The first version, a pill called GW1516, again produced the “fat burning” effect, but no change on exercise performance until the team started training the mice with long treadmill sessions. At the end of a series of these, the mice given the drug were running 77% longer than those training without its benefits.
The latest drug, AICAR, goes one step further, finding a different way to act on the same muscle cell mechanism. This time the mice did not need to train – after just four weeks on the drug, they ran 44% further on their treadmills without any prior exercise.
Both versions could one day serve a purpose in humans, said Professor Evans.
“If you like exercise, you like the idea of getting ‘more bang for your buck’,” he said.
“If you don’t like exercise, you love the idea of getting the benefits from a pill,” he said.
He said the most obvious potential use was in conditions, such as diabetes, where exercise was a proven benefit.
“Almost no-one gets the recommended 40 minutes to an hour per day of exercise – for these people, if there was a way to mimic exercise, it would make the quality of exercise they do more efficient.”
However, Colin Palmer, a professor of pharmacogenetics at the University of Dundee, said that the idea of the drug had proved controversial.
It has been hailed as the couch potato’s dream, giving the benefits of exercise without leaving the sofa.
But its arrival on pharmacy shelves is believed to be several years away.
The researchers say their work offers hope for the obese, those with muscle-wasting diseases and those who cannot exercise because of a medical condition. The pills could also offer the benefits of exercise to those who cannot find time to fit the gym into their hectic working day.
GW1516 was being tested as a cholesterol-lowering pill. However, trials were halted over concerns about safety.
Professor Stephen Bloom, of Imperial College London, said: ‘Even if these particular agents turn out to have side-effects, the proof of principle is still there and we can look forward to someone making something which is safe and effective.’
Dr Colin Waine, of the National Obesity Forum, called the research ‘important’ but added that at the moment the best way to tackle weight problems was with healthy eating and increased physical activity.