If you're in doubt, its true- Building lean muscle can take years for beginners and regular gym-goers alike and it doesn't matter if you are skinny or fat.
In my own fitness adventure and as a trainer, it took me years to figure out how to build muscle, particularly my lean muscle mass, and gain weight.
Think of gaining weight as a ratio of lean body mass/muscle mass to body fat, this will make it easy for you to visualize, you should typically maintain a 12% body fat for a ripped body, so aim for a 6:1 ratio.
Here are some important pointers that I use and teach, that have helped make significant muscle gains possible even for the really tough muscle-gainers.
You should see significant changes in your lean muscle mass if you use make good use of these pointers: 1) Focus on high intensity workouts, 3-4 days a week for a maximum of 1 hour, your body typically gets catabolic (releasing energy) after this stage; you want to be in an anabolic state.
High intensity triggers muscle growth because it gets those muscles to work! 2) Get into the habit of using supersets in your muscle building workouts, for example: 15 push-ups immediately followed by 15 squats then a 20 second break; repeat 3 times.
Breaking up your exercises into supersets can be highly effective and you should play around with it for fun and for maximum results.
3) Forget isolation exercises entirely and focus 95% of your workouts toward multi-joint exercises, multi joint exercises always take care of specific parts(such as abs,triceps-that you would have otherwise been trying to isolate) this is why you would have seen amazing results after pull-ups or using a kettle ball, kettle balls are the bomb by the way! I have compiled a list of multi-joint exercises you could use, in my next article.
4) Eat right; this is where even those with the determination of Edmund Hillary can lose interest, that's because information is never specific to the individual here.
However if you pay close attention to the basics, you will be set.
There are only 2-simply eat smaller meals a day (at least 5 a day) and make sure they are real whole foods such as eggs, meats, fruits, vegetables, seeds(sunflower),etc.
instead of processed protein powders, chemical-laden bars, and meal bars.
These are basic tips that should be kept in mind What's next? Work at it, keep learning and be creative, working out is a fun activity and should never be the same every day.