很多研究总是会告诉你锻炼对机体健康有多重要，其不仅能帮助抵御心脏病、中风、糖尿病以及很多癌症（乳腺癌和结肠癌等）；但近日，一项刊登在国际杂志New England Journal of Medicine上的研究报告中，研究人员发现，对于更广泛的癌症群体而言，一个更重要的预防性因素则是体重指数(BMI)低于25。
BMI是测定体脂的指数，将个体的身高和体重进行综合分析就能得出一个人的BMI值，BMI值较低意味着机体脂肪较少；研究报告指出，如果个体处于过重状态（BMI位于25-29.9之间），其健康风险会增加50%；如果处于肥胖状态（BMI不低于30），那么个体的健康风险将会增加至80%。
Exercise your right to fight disease
by Len Canter, Healthday Reporter
(HealthDay)—Research consistently tells you just how important exercise is for health. It can help head off heart disease, stroke, diabetes and many types of cancer, including breast and colon cancers.
A report published in the New England Journal of Medicine found that another important prevention factor for an even wider group of cancers is having a body mass index (BMI) below 25. BMI is a measure of body fat that takes into account a person's height and weight. A low BMI means you have less fat on your body.
The report also showed that health risks can be up to 50 percent higher if you're overweight (with a BMI between 25 and 29.9)—and up to 80 percent higher if you're obese (with a BMI of 30 and over).
Indeed, a high BMI may be to blame for nearly 4 percent of all cancer cases, according to another study, published in The Lancet Oncology.
There's no doubt that diet and exercise work together to lower BMI. Besides cutting calories, to lose weight you need at least 30 minutes of moderate physical activity most days of the week, and 60 to 90 minutes a day to maintain a loss.
But don't stop there. Other research has found that the more exercise you do, the more you can reduce your risk for many diseases. Indeed, people whose physical activity levels were several times higher than the recommended minimum had the greatest reductions in risk.
Of course, it's hard for everyday Americans to spend hours a day working out unless you have a treadmill workstation on the job, for instance. But try to take a few three- to five-minute exercise breaks throughout the day, and look for opportunities for more activity on the weekends, from family hikes to ski and camping trips.