mfp for kids?

(Not really.)

Is anyone aware of any sites similar to mfp, but aimed towards the tween set? My son is 13 and is small of stature--we have always struggled with him getting enough calories in a day (he loves fruit and salads are one of his favorite lunches). He is also very active--right now he is playing lacrosse 2-3x per week and skiing competitively on the weekends. We recently had a setback in that he just had braces put on his teeth so his eating has become a little particular again. At the same time, he is becoming aware of all of the boys his age who are so much taller and larger than he is--yes, I know genetics and puberty play a huge role here--but quite simply, not getting enough calories from quality food and not getting enough sleep is depriving his body of the opportunity to grow. I know that he needs to eat very differently than I do, and right now it's complicated enough to manage my own food diary. Are there any websites out there set up like mfp, with a food diary and possibly a fitness/workout tracker, maybe without the social media aspect, but aimed towards those who are under 18? Definitely not as concerned about weight loss for him at this point--more about, "if you're this active, then you need to make sure you take in this many calories, this many grams of protein to fuel your body..." I am hoping to help make him more accountable for what he eats and teach him to have a healthy relationship with food and exercise for the rest of his life.

Thanks!