I tried a Couch to 5K last fall with a group, coaches and the whole works, but only made it 8 weeks before getting an ankle stress fracture. Up until then I was doing good with the exception of having some pain in my lower shins. If you are out of shape and haven't ran or walked regularly then the C25K is hard on your body. I would do a good walking program first. But if you are use to walking 1-3 miles regularly then it'll probably be okay. But definitely do a good warm up before any running. Do only dynamic stretching, not static stretching. Static is what you do afterwords. I wasn't losing weight fast in those 8 weeks, but I was losing. I had lost about 6 pounds in those 8 weeks. But the C25K is only three days a week, so if you want to lose more you of course need to modify your diet and add a couple of days of walking, but don't do more than 3 days of running. This is what the coaches told me in the group for the C25K program. Hope this helps.