Macronutrients Micronutrients Energetic values of food Importance of exercise in body composition/recomposition (eating protein doesn't = huge person, etc) Hydration
There's 5, that probably covers most of it. Could probably throw in "healthy food choices", "antioxidants", "essential nutrients" as well if you wanted to. Not quite sure how long you have, what you're trying to actually teach, etc...
Basics are basics and I don't really see the need to change much for the lower grades, except maybe to specifically address junk foods, and the importance of limiting them (not necessarily avoiding them like the plague, depending on your take on it.)
With the high schoolers, 9-12th, I'd consider branching out to issues related to nutrition:
A basic intro to supplements (since there's a good chance any student-athletes are taking protein, maybe creatine, and possibly considering other stuff.) You could cover how to prioritize supplements so that they serve as a... supplement... to already solid training and nutrition, and how to avoid crappy supps.
The role of exercise (weight training, cardio, sport specific) and how nutrition can effect performance and results. You could bring up "Tons of exercise plus zero calories doesn't make you lose weight" or "Just because athletes burn more calories doesn't mean they should be fueled by Snickers bars".
I'd probably explain how insulin is a shuttle for nutrients etc. And what spikes insulin, the value of keeping insulin levels steady throughout the day along with the value of strategically spiking it.
I personally didn't know that in highschool, and I think it would have helped me alot back then.
trans fats...explain to them what they are, why they are horrible for you, and how you can spot them on ingredients lists. The amount of trans fats in kids twinkies, cakes, cookies, peanut butter, etc. that would be wise.
Yer. Teach them about good fats and bad fats. Also give the kiddies an idea of what to eat for afternoon snacks. I remember when I was that age and when i got home from school i used to smash the pantry, going for the chocolate first
I don'tknow if this would be applicable to the younger kids, but maybe the older ones.... I work with high school kids, so of course I get steroid questions. The best answer I have found, is to explain that at their current age, their natural hormone levels are ideal to get big and muscular, and that 'older' people take steroids in an attempt to recreate the environement that they have right now.
So instead of thinking sterods will help, they should be taking advantage of their natural situtation and eating right and busting their ass in the gym. (then I throw in some stuff about how playing with their hormones now will lower their naural output later on -lol)