It's no coincidence that the best-funded rehab clinics usually offer aerobics and yoga classes. The classic good-health trifecta (exercise, eat well, sleep well) is the crux of almost all successful addiction treatments. It also works for our deadliest legal addiction - exercise does, indeed, reduce smokers' cravings, and a new study reveals the mechanism, if not the root, of this downturn.

Researchers at the University of Exeter placed ten regular smokers on an exercise bike for a short workout after depriving them of their drug of choice for more than 12 hours. These study authors then performed fMRI scans on the subjects while they viewed a series of images, some of which were specifically designed to elicit nicotine cravings in smokers. The subjects went through the scan a second time at a later date without spending any time on the exercise bike. They were asked to describe the intensity of their physical cravings after both tests.

The study's results are simple and convincing: the brain centers responsible for addiction responses were far more active when the subjects had not exercised at all. And, by their own admission, their desire for nicotine was considerably less severe after they spent time on the bike. Even these short bursts of physical activity appear to divert the body's attentions from its long-standing dependence. Why? One theory holds that exercise provides the body with enough of the pleasure hormone dopamine to reduce the "withdrawal" deficit that creates those urges. Exercise may also divert blood flow from the brain regions responsible for creating the reward/pleasure system.

Those looking to kick the habit can't spend ten minutes on a stationary bike every time they crave a cigarette. But the point cannot be repeated often enough: healthy diet, sufficient sleep and especially regular exercise are absolutely essential to break an addiction. Their collected benefits certainly outweigh those of necessary evils like nicotine patches or gums.