Many young men between the ages of 16-18 start thinking about buying a pair of dumbbells to help them build more muscle and attract members of the opposite sex.
Indeed I myself bought my first set of dumbbells when I was around 17 because I had always been really skinny up until then.
However there is a difference between building a little bit of muscle, and bulking up with some serious muscle mass, and the reality is that it is very difficult to bulk up using a standard set of dumbbells.
The trouble is that when you go to a store and buy one of these dumbbell sets, they will generally be 20kg dumbbells, which are fine if you are just starting out because they will definitely give you increased muscle tone and definition if you train regularly.
The problem is that you will eventually outgrow them, and there will come a point when you need to start lifting heavier weights because your exercises have become too easy.
Plus you will find that squatting, deadlifts and bench presses, which are some of the most effective exercises you can do if you want to bulk up, will not generate any real results using such light weights.
Bulking up requires a combination of excess calorie consumption and some serious muscle-building work, and lifting a fairly light set of dumbbells, no matter which exercises you do, are not really going to cut it.
You can bulk up just by eating 3000 calories or more per day, for example, but you are not going to build any muscle mass doing this. You are just going to get fat.
If, on the other hand, you consume lots of calories, and ideally lots of clean high-protein foods, and combine this with some serious lifting in the gym using barbells and various different exercise machines, for instance, you will gain weight and build muscle at the same time.
Barbells enable you to lift a lot more weight, but the good thing about going to a gym is that they will often have much heavier dumbbells as well.
So you could argue that it is possible to bulk up (with muscle) using dumbbells providing that you use some of the heavier 30-40kg dumbbells that you might find in your local gym, and maybe combine this with squats, deadlifts, bench presses and other gym work.