Body Composition
The only time you should ever want to gain fat is when you're in the 2% range and your organs start to lose their cushioning. I've only ever met one guy who needed to do this. (He now has a girlfriend who cooks and he's up to a whopping 3% now, but I digress). You can really never be too skinny for running or biking (except for the 2% thing), and it doesn't take a whole lot of upper body mass to swim fast for long distances (sprinters are different, of course). If you want to bulk up for the ladies, start lifting and taking protein to build muscle, but definitely don't make an effort to put on fat.
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-Matt
Not fast enough.
I would echo UFTriGator. Just from the numbers, 8.6% body fat and 6'3" sound like pretty darn good numbers for a triathlete (or any endurance athlete in general). I think weights are great for triathletes, just don't get carried away by all the muscle in the gym and copy the guys with the 20" biceps. Find a good lifting plan for endurance athletes and bring it with you so you so you'll stick with it. That said, many pros do fine never touching weights, so it's not mandatory (for me it's more vanity and habit, coming from a football background).


I'l be as brief as possible...
I am a 19 male. I have a BMI of about 21.5 and my body fat is at about 8.6% and I am 6'3". Are those levels ok? I feel I am kinda to skinny, and if so, what should I gain weight on (fat, muscle, both?)?
Thanks in advance
-Nayo