I am 5’4" and I need to lose 20 pounds. I’m starting to run 3 miles a day and I eat about 1800 calories a day, and about 75% of my daily carbs. How long would it take me, if I continuously ran 3 miles a day, to burn off 20 pounds of fat?
Running is a bearing exercise so, depending on your weight, you could burn 80, 100, 150 calories…per mile. 3 miles could burn 240 or 450 calories. You need to burn 3,500 calories for each pound of fat reserves that you wish to lose. 20 pounds would be 70,000 calories.
Use the Activity Calculator (link in source).
I don’t understand what you meant by “75% of my daily carbs”.