David, your son needs to be sure he’s taking care of two things first: diet and training. Most super skinny guys simply don’t eat enough. Oh sure, they SAY they eat a lot, but once you get them to start keeping a log of daily caloric intake and macros, they find they haven’t been getting as much as they think, usually overall calories are low, protein intake is low, they skip breakfast etc… Check out my “Dawg School” column, issue 105 for more tips. Second, you didn’t mention if he’s weight training regularly and properly using compound movements like squats and deadlifts. Make sure he’s taking care of that aspect, too.
Now, you can look into supplements. If his problem stems from his diet, then Grow! is a convenient and easy way to add in calories and quality protein. It’s just food after all. Have him drink two a day between regular meals. Use the “buy 2, get 1 free” Biotest deal and it’s about $1.66 per serving, cheaper than Taco Bell! He may also want to experiment with Cy Willson’s theory of taking in half of his daily protein intake after training. Not proven yet, but very interesting. Cy talks about this is issue 109. Check the “Previous Issues” section.
Tribex-500 has been university tested on trained athletes in the 21 to 24 age range. I believe the average lean muscle gain was 6 pounds and all lost some fat and gained a little strength. (Check issue #113 for details.) So Tribex appears to work for young guys, too. But how about as young as 18? I’m not sure. I’ve seen 18 year old guys do well on Tribex, but did they really need it? Again, I don’t know. I would probably suggest a creatine product like Ribose-C first.
Whatever you decide, remember, diet (including Grow!) and training first. Then he can start experimenting with other supplements. Hope this helps. - Chris