Training or weight loss

I have been running regularly for 6 months - I now run 5 times a week and cover around 20 miles with two longish runs of 6 miles and three 3 mile runs. I am at least 2 stone over-weight and probably need to lose 3 to get to my ideal. So, should I be doing 5 easy paced (according to the McMillan formula) runs to burn fat and train when I am closer to my goal weight? Or, mix it up a bit with easy paced long runs and tempo/fartlek/hills as well?
I have run my first race - a multi-terrain 4.5 miler - that I will complete 3 more times this year and aim to run three other 10k races spread throughout the season.
Your ideas will be most welcome.

personally i'd mix it up a bit. try and make one of your long runs a bit longer (if you can work up to about 8 miles it will really help for 10ks) keep the long runs easy paced. then add in some tempo/fartlek/hills to your shorter runs. make sure you keep some of them easy though. and build up the harder work slowly.

in order to lose weight while you are training you will most likely still need to look at how much you are eating and see if it is reasonable for the exercise you are doing. its oh so very easy to pig out following a run and eat way more than you've burned off (believe me i'm an expert at it).

try for 300-500 calories less per day than you use and the weight should come off nicely.

thanks for your comments. i intend running an 8 mile route this saturday and have run a mix of runs this week: 5k easy, 5k race against a previous run - used GARMIN virtual partner, another 5k easy and a negative split 3 miles running each mile faster than the previous one. i suppopse by adding the 8 mile easy, i can do 'workouts' without impacting the overall training effect. well, i hope so anyway.