Is it effective to run the same distance (10 km, for instance) every time at the same speed or should I increase the intensity of training? My goal is to lose weight and stay healthy.
Master of Sports of International class in track and field athletics, winner of the Zurich marathon, participant of the Beijing 2008 Summer Olympics, multiple European Cup and Russian championships medalist, coach of the school “I Love Running”
In terms of energy consumption the duration of running is important. Too short runs don't help you to burn fats as metabolism of fats starts when the glycogen stores are depleted but it takes some time.
If we consider your case and 10 km running these goals are easy to achieve. So, if you don't want to increase your running distance, don't do it. It's more important to keep stable training frequency (but at least 2 trainings a week). In this case, I think, the goals you set - to lose weight and stay healthy - will almost certainly be achieved.