There are often posts here from people who are starting Couch to 5k in conjunction with Weight Watchers, Slimming World or self-managed diet changes to lose weight. There are also lots of responses that Couch to 5k is not on its own a weight loss programme. Remember, newly-built muscle is denser than the fat it replaced.
I agree as I have lost a modest amount of weight (about half a stone) and only from about week 6 onwards. HOWEVER...I have noticed a much more marked change in my body dimensions. Clothes fit better, the belt has come in a notch or two and I can fit in my interview suit again.
So, I would urge those of you looking to lose weight instead to focus on your measurements. I really wish I had measured my waist, hips, thighs, etc. at the start of the plan so I had a quantified reduction in black and white on paper now. It's great motivation to continue running when you have the numbers to look at as well as feeling fitter and not straining to do up your jeans!
Also, don't get obsessed with weighing and measuring every day as normal small fluctuations can be disheartening.