bad news for smokers

You can't quit halfway:

When you quit smoking, it's all or nothing, says Scientific American. In a Norwegian study of 51,000 people over a 20-year period, researchers found that just cutting back on cigarettes didn't reduce the risk of death. Those who quit completely significantly boosted their long-term health. But those who cut their pack-a-day habit by half suffered the same consequences as those who still smoke the whole pack. Both groups suffered impaired cardiovascular health and serious heart and lung damage.

While you're quitting, it's okay to start off by cutting back so that withdrawal symptoms are not severe, says Dr. Kjell Bjartveit, who led the study. But to reap the health benefits, stop smoking altogether, says Bjartveit. "You can't give your health a better present."