I've lost 20 lbs since July running nearly every day. I'm 5'9" and went from just over 180lbs to 160lbs. 1/2 M and shorter distances it has helped greatly. Longer than 1/2M and I fade worse than I used to when I ran on high glycemic carbs.
My running week changed from doing 2 - 3 longer distance days per week where I did a 2-3 hour run and the remaining days were short easy runs of 1-1.5 hours to going to a week of 2 sprint interval days and 4-5 easy run days of hour long runs. I had a
PR in a 5K last August. The old mark had lasted over 3 years. I have a 10k Saturday and I hope to really challenge the
PR for that distance.
You want to avoid long sustained efforts at an average heart rate of more than 80% max effort. Longer sustained efforts like that promote cortisol production which will stall fat loss. Do a warm up run before sprinting, a cool down jog after each sprint and a cool down run after the intervals to keep the average heart rate for the workout in the proper range of 75% of max. Easy effort runs should be just that. Average heart rate of less than 75%. For me the correct amount of time now is 1 - 1.5 hours. I could go longer now that the temperatures are cooler without experiencing a drift upwards in rate or having to slow way down to keep the heart rate in range but I don't see the benefit to it on a regular, planned basis.