It’s a battle that’s all too familiar to millions of people – on one side is a packet of biscuits, the sofa and a DVD, on the other a work-out at the gym.
And all too often the gym is on the losing side.
But now scientists think they may have found a way to make opting for the weights and treadmill the winner far more often – and it almost sounds too good to be true.
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Researchers believe that it may be possible to manufacture a pill that motivates people to exercise.
The secret, says a team from the University of Zurich in Switzerland, is a brain hormone called erythropoietin (Epo).
When this was elevated in mice, it made them run around a lot harder.
"Here we show that Epo increases the motivation to exercise," said lead author Max Gassmann. "Most probably, Epo has a general effect on a person's mood and might be used in patients suffering from depression and related diseases."
To make this discovery, Gassmann and colleagues used three types of mice: those that received no treatment, those that were injected with human Epo, and those that were genetically modified to produce human Epo in the brain.
Compared to the mice that did not have any increase in Epo, both mouse groups harboring human Epo in the brain showed significantly higher running performance.
A report of the study appeared online in The FASEB Journal.
Its Editor-in-Chief, Gerald Weissmann, said: “If you can't put exercise in a pill, then maybe you can put the motivation to exercise in a pill instead.
“As more and more people become overweight and obese, we must attack the problem from all angles. Maybe the day will come when gyms are as easily found as fast food restaurants."