Eating is not enough..

Skinny Guy Confessions: 

Looking back upon those years, it's easy to see what I was doing wrong and why I wasn't gaining weight (and muscle). Here are the major reasons why I wasn't making progress:

Cardio Overkill - I was exercising way too much. WAY too much. During the Summer months I was outside from sun up to sun down, running, playing baseball or basketball, or swimming.

When I wasn't outside, I was indoors doing some form of cardio - step ups, jumping rope, or even aerobics (yes, it was the early 80s). It wasn't unusual for me to run 3 miles a day, do 45 minutes of step ups, and play baseball for 4 hours. This was just another typical day for me.

So here's the problem: while I was certainly fit and healthy from all that exercise, I was expending a crazy amount of calories. Am I telling you that I should have stopped exercising completely? Of course not. Cardio work is a great way to improve overall health. The problem with doing "too much" cardio (and general exercise) is that it conflicts with another one of your primary goals - gaining weight.

Research backs up common sense on this subject. (1) A recent meta-analysis on the impact of cardiovascular exercise on resistance training determined:

Our results indicate that interference effects of endurance training are a factor of the modality, frequency, and duration of the endurance training selected.

The bottom line is that when you run a lot of cardio concurrently with your resistance training, it impacts results. The more cardiovascular work you do, the greater the tendency for it to impact your results.

If your primary goal is to gain weight and build muscle, then it would make sense to not push cardio too much. This is a competing goal; one that is in direct conflict with your weight gain goal. Because of this it makes sense to minimize the amount of cardio you do.

If you are a skinny guy, keep cardio sessions to "about" 3-4 per week, for 20 to 30 minutes each. If you play sports, or have an active lifestyle and can't really reduce cardio, then it's time to improve your diet.