Changing up training from distance running to high intensity training

[turfsire]

Hey all,
I recently open at thread about my thyroid I was sure was something wrong I had blood taken and everything is near norm
My training is to run 5k a day 4 or 5 days a week which was great because I have a dog killing two birds with one stone
But my knowledge of the body is well behind only recently I have read up about high intensity training I guess the 5k runs do work as far as cardio but my metabolism might have been slowed down "I guess my body said what the hell is going on here..I have to reserve some fat with all this crazy running"
I have a few questions regarding high intensity
Can I knock off the weight with Sprints or such, what about my metabolism can I raise it ? of course there's a lot of other mitigating things that could be of no use.
I'll just give a run down about myself 37 year old male 5 foot 7 weigh between 178 and 180 pounds my diet is good enough I reckon I don't need any trash food maybe fast food pizza once a month I don't sit idle neither from work and of course the dog no small feat
I love running I think it's such a great destresser but it may be impacting on me.
A lot of other training is alien to me, I'm thinking of maybe getting 12 kilo kettlebell and use it with Sprints .. my goal would be to knock off at least 15 pounds looking in the mirror I can see it around my waist..I used to box professionally and boxed between 154 160 ..back in the day weight came off a lot easier not so much now,
I am thinking about going on oral steroids like clenbuterol and mix it up with a good diet and high intensity but not sure though ..a lot of buts here
Any advice would be great thanks