Most people take a very singular approach to training. They believe that lifting weights is for strength and cardio is for endurance and fat loss. Well, this is completely false. I know from experience that you can in fact use dumbbells for strength, endurance, and fat loss.
The key lies in HOW you organize your workouts. There are two main things you need to consider: 1) What exercises you use, and 2) what intensity techniques you use. Most individuals use ineffective exercises and absolutely NO intensity techniques.
When it comes to the kinds of exercises you want to use, stick to large, compound movements. Compound movements are exercises that work more than one muscle group at a time. This includes chest press and bent over row.
When you're recruiting more muscle groups, you're working a lot harder than when you perform isolation exercises. Try to perform a set of dumbbell bench presses. The compare it to bicep curls. Which exercise raises your heart rate and causes you to work the hardest?
One of the best intensity techniques out there is something called "Non-Competing Supersets." This is where you perform two exercises back to back that do not work the same muscle group. A good example of a non-competing superset would performing a set of dumbbell bench presses followed by a set of bent over rows.
Using this method alone, you can actually build muscle and lose fat at the same time! You won't be a bodybuilder, but you'll be ripped. Let me just mention that when you train like this, the workouts tend to be super difficult.