A、The upward tendency of obesity. B、The rising level of heart attack. C、The growing number of suicide cases. D、More and more wor

Compared with jogging in early mornings or lunchtime trips to the gym,(23)standing up on the phone and walk over to speak to colleagues are much more effective in losing weight for office workers, according to official advice.
    The Government has drawn up workplace exercise guidelines to tackle concerns that most of us are spending too much time sitting down.(23)This could include taking the stairs rather than waiting for the lift, and cycling or walking to work. Staff are also advised to stand up every 30 to 40 minutes when talking on the phone to break up the amount of time they spend sitting down.
     (24)The guidelines have been issued by the Department of Health, concerning about rising levels of obesity. Only a third of adults take the recommended amount of exercise, which amounts to at least 30 minutes for five days a week. And around six in ten are either overweight or obese—predicted to rise to nine in ten by 2050.
    Pro. Fiona Bull, from the School of Sport, Exercise and Health Sciences at Loughborough University, who helped draw up the guidelines, said there was growing evidence that long periods spent sitting down could lead to health problems. She added: "Every 30 to 40 minutes, stand up while taking that phone call. Don’t send the e-mail, walk over and speak to your colleague. "
    Recent studies have shown that desk-bound workers who spend long periods of time sitting down are more likely to die of heart problems, even if they exercise regularly. And last month,(25)Canadian scientists found that women who spent more than six hours a day at a desk were 40% more likely to die of heart disease or cancer than those who didn’t.
23. What advices are over given by workplace exercise guidelines?
24. What do the guidelines concern about?
25. What did Canadian scientists find?