Fifty years ago, most people's daily levels of activity were equivalent to walking three to five miles a day; today, the average person fails to cover that distance in a week.

    It's no wonder the incidence of obesity has soared - with serious implications for health.

    The culprit? Inertia. What we have gained in convenience from labour-saving devices over the past half-century, we have paid for in terms of a sharp decline in physical activity.

    We use cars, buses or trains to get to work; our children are driven to school; escalators and lifts have replaced conventional stairs in shopping centres, offices and apartment blocks.

    Washing machines, vacuum cleaners, dishwashers and electric mowers all minimise the effort required to maintain a clean and tidy home.

    Television has us tethered to the sofa.

    Almost one third of adults spend over ten hours sitting down every day, adding up to a staggering average of 32 years and four months over a lifetime.

    Hardly surprising, then, that researchers blame this sedentary lifestyle for our weight gain.

    Of course, our diets have changed, too, but the fact is we consume fewer calories now than in the 1960s.

    Our waistlines are expanding for one major reason: increasing inactivity.

    So what is the solution?

    The secret is integrated exercise. This involves going about your normal daily life - but doing it with more gusto.

    It might mean standing to answer the phone and pacing the room, tapping your feet on the floor as you work.

    It means never taking the car when you could walk; it means standing on short train and bus journeys, or walking at a pace where you feel you might break into a run if you were to go any faster.

    A Dutch study found that people who spend more time doing moderate, integrated-style exercise burned more calories than those who performed shorter, sharper workouts.

    半个世纪前，大多数人每天的活动量相当于步行三至五英里，而如今，普通人一周的活动量还不到这个水平。

    所以肥胖率的上升不足为奇，而这一问题则对健康造成了严重影响。

    罪魁祸首是谁？懒惰！半个世纪以来，我们从各种节省人力的设备中得到很多便利，但这是以我们身体活动的大大减少为代价的。

    我们上班要么开车、要么乘公交或坐城铁；我们开车送孩子上学；购物中心、办公大楼和公寓里传统的楼梯都换成了扶梯和电梯。

    洗衣机、吸尘器、洗碗机和除草机让我们不费力气就能保持家庭整洁。

    电视机让我们陷入沙发，不能自拔。

    近三分之一的成年人每天坐着的时间超过十小时，照此计算，他们一生中坐着的时间竟达到三十二年零四个月！

    所以，研究人员将发胖归咎于这种久坐的生活习惯不无道理。

    当然，我们的饮食也发生了变化，但事实在于，与上世纪60年代相比，如今我们消耗的能量减少了。

    身体活动的日益减少是我们腰围见长的一个主要原因。

    那么如何解决这个问题呢？

    秘诀就是“综合性锻炼”。这得从你的日常生活做起——但一定要充满热情地去做。

    比如，你可以站着接电话、可以在房间里溜达、办公时双脚可以拍拍地板。

    可以步行时，绝对不要“以车代步”；乘短途火车和坐公交车时最好站着；快步走，以再快一点就会跑起来的速度走路。

    荷兰一项研究发现，经常进行适度综合性锻炼的人比在短时间内进行高强度健身的人消耗的热量多。