阅读下面材料，在空白处填入适当的内容或空号内单词的正确形式。
Many weight loss programs seem attractive to people. But for most people        are overweight, the results are so       (limit) that they will give up long before achieving any realistic results. It turns out that the programs are practically of no use. You lose weight for a while, only         (gain) back more weight when you stop your weight loss program. This is       such programs are not natural. Is there a natural weight loss solution?
A sure way of achieving natural weight loss is to increase       amount of exercise you get every day.         , this doesn’t necessarily mean spending hours at the gym         in front of a weight loss video. Increase your weight levels       (nature) by walking or biking short distances instead of driving, or by taking the stairs instead of the elevator. There are even exercise that you can do while        (sit) at your desk. All of these activities can burn extra calories        taking up too much time.