Me and one of my girlfriends tested doing just cardio versus cardio and weights....We did 30 minutes of cardio for 5 days a week, over a period of 2 weeks. We did not change our diets at all. We did not loose any weight at all.
The past one month we have been doing a total of 30 minutes of cardio, plus 30 minutes of weight training. She has lost a total of 7 pounds in 3 weeks and I have lost 2 inches off my waist. And we've been eating the exact same as we were when just doing cardio
I asked my trainer why that is. He said that more muscle burns more calories, so if you are just doing cardio all you are really doing is just increasing your metabolism and improving your heart rate.
He also said never to measure weight loss in pounds. Do it in inches. Because muscle weights more than fat, the scales may not show that you are losing any weight. But measure yourself at the beginning of the month, try doing 30 mins of cardio, and 30 minutes of weights, then measure yourself at the end of the month. See what kind of results you could get.
Good luck to you in the weight loss!!