It will be useful. If you want to lose weight, you'd better run more than 4000 meters for more than 45 minutes to achieve the effect of losing weight. At first, you will lose water in your body. Finally, you will lose body fat. You run for 30 minutes, which is probably the time when you just want to lose weight. So, if you run for 30 minutes, you won't lose weight at all. Even if there is, it is rare.