I was one of the lucky children diagnosed with PKU. My parents took the disorder seriously and immediately changed their entire lifestyle for me (and my sister, who has PKU too). Before I got into elementary school, I didn't know that people ate any different than me and my sister. I knew there were things that I couldn't have, but I thought that happened to everyone.
When I started school, it was a little tricky. My mom frequently met with teachers to make sure they understood they couldn't feed me anything during the schoolday. Kids that I went to school with were curious. My mom took the time to make "special PKU treats" for everyone in my class every year of elementary school. This let the other kids know that I do eat good food, it's just different.
I knew what I could and couldn't eat, and in middle school I pretty much kept to myself about my diet. Awkward years, I'm glad I am not at that stage of my life anymore :)
When I got to highschool, I was still with a lot of the kids I went to elementary school with and they remembered a little about my diet, but there were a ton of other people that thought I was a little weird. Following what my mother did, I decided to get with all the science teachers in the highschool and tell them that I would give a lesson on PKU, the genetics and the lifestyle. The teachers were all for it, and so for a couple days, I was excused from classes and I got a period to teach my peers about PKU. The students were all interested in it, and asked tons of questions. It's not like diabetes, people aren't very familiar with what my lifestyle is like. (I actually have a more severe form of PKU and my diet is very restricted.) Being a self conscious female, I was assuming that I would get made fun of and the more popular kids would just laugh at me. They didn't. It was a great experience.
A lot of my life people just didn't understand what PKU is. They might have made fun of my formula, or something that I regularly ate that was different, but I always tried to turn things around. When I was about 15 years old, I went camping with a bunch of my friends and their parents. It was just after dinner and my sister and I were told to "drink our formula before we can go play" We had about 6 or 7 of our friends lined up waiting for us to finish our formula. (It was back in the day when it was NASTY and it took us a long time to drink)
One of our friends asked why we didn't just chug it and get on with our lives. It gave me a great idea. I went inside the camper and grabbed a stack of Dixie cups. I set a cup out for everyone who was there and I filled about half the cup up. If they were going to make fun of me and my sister, they were at least going to get a taste of what we had to drink every day!
They all took their "shot" at the same time. Very few of them swallowed the whole cup. We were never made fun of again for drinking formula slowly.
I guess my point being here through all this jabber is this: you're stuck with this diet (or else you lose brain cells), there's nothing you can do to change your situation so you might as well make the most of it. Teach people what you're going through so they are informed. Don't give people a chance to make fun of you or pick on you. Be stronger than them. Get them involved, give them an idea of how many mg of phe things have in them. See how much PHE they are taking in, just for fun! The more your friends learn, the more they are able to keep you line when you are tempted to go "off diet" one day.
I will occasionally run into people from school through Facebook or when I am back in my hometown. Those people will actually come up and ask about my diet, maybe see if they can score some of the candies my mom used to make.
Sharing your situation is better than going through 13 years of hiding in a corner. I started off shy, and now I will walk up to anyone and strike up a conversation. I am always willing to talk to children with PKU going through school.