From now on don’t increase by more than 10% per week. 
So you’re looking to lose the belly fat; running will be good, but running alone may not get rid of it. Add in exercises that challenge your core muscles, and really work on improving overall. You’d be surprised at how much core strength plays into strength in other areas of the body; I fully admit that I am much better at things like push-ups and squats when my core is also strong and in shape.
I’ve noticed that the combination of biking and running has positively affected my glutes, hips and legs. The core is stronger, but it’s going to take longer for that to be noticeably affected in my case.
I agree that adding in serious weight training is a good idea.
For me, running tends to slim me all over, but I don’t get a ton of definition from running alone; in fact, I tend to get better results from biking in my lower body. However, my best results for upper body has been a mixture of calisthenics, weight training, swimming, running and cycling. By doing different activities throughout the week/month, I’m challenging my body in different ways and I end up working most if not all my muscles. It also keeps me from getting bored.
To answer the OP, by the way: I’m actually nowhere near my lowest weight as an adult (probably 10 pounds over that, and 30 pounds over my ideal weight), but since I started running I have lost about 25 pounds and put on a ton of muscle. My pants size is smaller than it was in high school. Also, my cardio endurance is spectacular when compared to what it was at any prior point in my life.
But then, I started out significantly overweight and very significantly out of shape, so I’m sure my results aren’t typical.
Wow, that’s awesome. Congratulations. I’m also looking forward to having more energy.
As far as the core muscles thing goes, will yoga help for that? I can start DVRing the yoga shows.
Yoga helps (depending on the style), Pilates is better (imo).
If you want, I just wrote a paper for a University course on Core and Lumbo-Pelvic-Hip complex exercises that includes 10 exercise descriptions and what muscles they use. I could email it to you if you PM me.
Pick up any issue of Runner’s World; they run lots of articles on strengthening your core, hips, legs and so on.
Congratulations on starting running. I think you are going about it exactly right. The fact that you started running more than 1 mile is a good sign. Typically, one gets told to aim at a mile first, running while you can, and walking when you must.
While I don’t do Pilates (the classes don’t fit my schedule), I got owned in a plank contest (at close to three minutes) by one of the lasses who does, and I get pretty competitive about such things.
I prefer cross-training, too - circuit classes, weights, running, swimming and cycling. It gives me alternatives if weather/schedules/aching muscles get in the way.
But I know some guys who just run, and they get by pretty well, too.
Si
I wanted to chime in - if you find the C25 program too easy - start a couple of weeks into it and run faster during the run times - it makes it more challenging.
I started running again recently. The running I’ve done in my life has really helped my health. In my teens I pretty much had chronic bronchitis, but in my early 20’s I ran a lot for a few years and I stopped getting sick as much and I recoved from illness much faster. So one more good reason to run.
Now, I’m not following the reasoning people here have for running at 80% of max heart rate, or so you can carry on a conversation. Due to limited time (I have kids now) I no longer run for 2 hours at a time like I used to. Instead, I’ve been running 5km about 3 times a week. However, I do it as fast as I can and I get pretty close to my max heart rate for the last few km. If I only have 25 minutes to run I’m going to make the most of them. I’ve also read that running at faster speeds for shorter times burns more calories than running the same distance at a slower pace.
What, if anything is wrong with what I’m doing - or in offering it as a option to others?
You might look up High Intensity Interval Training. The idea is to run at a moderate pace for 5 minutes or so, then sprint up to 90%-95% max heart rate for 30 seconds, walk for 30 seconds, sprint 30 seconds, etc. Do 4 intervals at first, followed by a cool down jog. Then every couple weeks add on intervals.
That is supposed to burn more fat than a long steady run, and offer better training for sports like soccer or basketball which require quick changes of pace. It also takes a lot less time for plenty of workout.
Yes, you burn more calories over the same distance running more quickly over the same distance, but not a lot. However, it is not a particularly good idea to run fast all the time, because you are more likely to get injured. I suspect you are young enough to get away with it for a few years, though. A better idea would be too run hard 2-3 times a week, and then take the kids for a stroll on the days in between.
If you want to maximize how long your heart is near max, warm up, and then run intervals, trotting in-between. Your heart rate will stay elevated longer than if you just give one big push.
I agree with this and would guess the extra calorie burn to be about 25 - 50 calories or so.
I don’t think it’s a horrible idea to run close to your max if you’re younger and can handle it and or only doing it for such a short time, but you don’t burn calories the same way. If you don’t really care about that, then go for it. 25 minutes of hard running three times a week isn’t a big deal.