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.

    半個世紀前，大多數人每天的活動量相當于步行三至五英里，而如今，普通人一周的活動量還不到這個水平。

    所以肥胖率的上升不足為奇，而這一問題則對健康造成了嚴重影響。

    罪魁禍首是誰？懶惰！半個世紀以來，我們從各種節省人力的設備中得到很多便利，但這是以我們身體活動的大大減少為代價的。

    我們上班要么開車、要么乘公交或坐城鐵；我們開車送孩子上學；購物中心、辦公大樓和公寓里傳統的樓梯都換成了扶梯和電梯。

    洗衣機、吸塵器、洗碗機和除草機讓我們不費力氣就能保持家庭整潔。

    電視機讓我們陷入沙發，不能自拔。

    近三分之一的成年人每天坐著的時間超過十小時，照此計算，他們一生中坐著的時間竟達到三十二年零四個月！

    所以，研究人員將發胖歸咎于這種久坐的生活習慣不無道理。

    當然，我們的飲食也發生了變化，但事實在于，與上世紀60年代相比，如今我們消耗的能量減少了。

    身體活動的日益減少是我們腰圍見長的一個主要原因。

    那么如何解決這個問題呢？

    秘訣就是“綜合性鍛煉”。這得從你的日常生活做起——但一定要充滿熱情地去做。

    比如，你可以站著接電話、可以在房間里溜達、辦公時雙腳可以拍拍地板。

    可以步行時，絕對不要“以車代步”；乘短途火車和坐公交車時最好站著；快步走，以再快一點就會跑起來的速度走路。

    荷蘭一項研究發現，經常進行適度綜合性鍛煉的人比在短時間內進行高強度健身的人消耗的熱量多。