if u want to lose weight you have to run over 20 min and with a stlbae speed.Speed doesnt matter.If you cant run with 10 km/h thats fine.Go with 6km/h.I am overweight,i have 10 pounds more that i should have and i do like 40 minutes on treadmill and i run 8km/h.Doing more minutes on treadmill is good cause u burn fat.I lost like 10 pounds in 40 days!And you dont have to starve to death.The key for proper diet is to eat when u are hungry and avoid sugar as much as you can.