Some prefer to run indoors while others prefer to run outdoors. Some pick where to run based on what’s more fun to them or what they have access to.

There are specific differences between running on a treadmill and running out on the pavement.

Treadmill vs. Pavement Running

The treadmill is easier on your joints as the surface is cushioned for impact
You exert less force on a treadmill as the belt helps to pull your feet back
No resistance to overcome from the natural elements on a treadmill
If running outdoors for the first time, start out slow and progress
If you want to run in an outdoor event, do most of your training outdoors
Motivational benefits of a treadmill is that you can set a course and compete with time to finish it
Outdoor running areas are hard to find for some people
More space for your body in the open air as opposed to a smaller frame on a treadmill. Running in such a small space can cause your muscles to tighten up and other long term problems
Your pace slows down outside while treadmill is a forced pace

To make a long story short, do what you want, as long as you are moving if your goal is weight loss. For weight loss perform some form of resistance training circuit/interval style on alternate running days as well.

Natasha Linton
Top Rising Star in Personal Training
-National Fitness Hall of Fame and Museum