When I was 17, I weighed 120 kgs, and I knew it was time to start changing that.
So I read about nutrition and training daily, modified my eating schedule and startet working out. In 4 months, I lost about 40 kg. After the diet, I was exhausted and powerless. So I started eating a proper ammount of protein, got a good training program and started lifting weights.
Meanwhile a few years have passed and I gained about 20 kgs of muscle without using steroids or hormones.
The point is: Everyone can do it. You just gotta believe that you CAN do it!
The next time I'll give you a short glance about my eating schedule.