I am 28. Prior to training heavily, I was a competive swimmer through high school and college. I did the basic drills and cardio then. Mostly back, shoulder and ab work. I was about 184 then. Though my weight tended to move up in the winter months because I was not doing all the cardio or swim drills.
I started training heavy with weights right out of college for about 1.5 years. Then took a long lay off because I went through a relationship break up that left me depressed and second guessing myself. I lost a lot of weight during that time because I was eating at the most, twice a day. Many days, I only had just lunch for the whole day. But once I started training again and eating right, the muscles just started coming back.
One thing that I credit for most of my development is that I took the time to find out what works for me. Most people don't do that. Instead, they cling on to useless exercises their bodies don't respond to because they like to do them, their ego requires them to do them, or because they have conditioned to think they need to do them (i.e. squats, flat bench press, etc..)
Diet wise, I don't count calories. But I do eat a lot of protein. I keep my carbs low. I am not sure of the school of thought where some people say that you only need 1 gram or 1.5 grams of protein per weight. It has never been truly established that more protein builds more muscle. However, the extra protein does in handy for keeping the calories up so I can grow. If more protein does indeed equal more muscle, at least I have under control. I do rely on a lot of protein shakes to get this amount of protein each day.
I have posted what my exact diet was for a specific day in the past. You can search and find it. Maybe after Monday when I am back to eating "normal" I will post a thread on my day by day food intake.