a healthy diet and regular exercise may help to prevent obesity among children.take li ming for example.li ming used to be a heahhv boy, but over a year ago, he got into the habit of eating a lot of junk food and snacks. besides, he spent a lot of time lying on the sofa, watching tv, and did little exercise. as a result, he put on so much weight that he found it difficult to chimb stairs.

　　so li ming decided to change the unhealthy life style, ftc began to have balanced, healthy diet. itc also took part in various sports activities such as swimming, skating, running and playing baskellball. months later, li ming became as fit as before.