There are many variables to this question, such as running intensity, your current health and your eating habits. In order to lose weight, it's a good idea to focus on all 3 of these areas if you truly want to see noticeable results.
Try this. You could potentially lose 16 pounds in 2 weeks. Once you're at a satisfactory weight, lower the intensity but still be consistent with the routine.
1. Eat consistently(about every hour and a half) and eat low carb and low fat food.
2. Exercise daily(run or walk about 3 miles a day, make the intensity comfortable). After exercising it's a good idea to eat foods with carbohydrates, such as pasta.
Losing weight and being healthy is a lifestyle not an activity.