"Tired" When Lifting Weights But I Don't Know Why

[BarryBeeBenson]

I love this website. Folks here always give me insightful answers, not just a copy / paste from another website.

Anyway, I'm 16 and play Left Tackle for a 6A school in Tennessee. I need to increase my upper body strength, more so in the bicep / tricep areas rather than lats and neck. I've had a problem for a while, but it just recently got worse: My arms / lats are immediately fatigued / tired when I start lifting weights, even if it is light weight. I get a full nights rest and 3 protein-rich meals a day, so it's not like I'm starving myself of sleep or nutrition.
Is there something I should eat / drink before working out upper body or am I missing something else altogether? Keep in mind my lower body doesn't do that, I can do squats and leg press all day long without these symptoms.

I'm a bit at a loss because I know anyone I know personally would say I need to eat more, and that's just not the case. I eat a lot, but I don't overeat; I only eat when I'm hungry.
A final note is that I don't take supplements other than a lot of protein shake powder.

[HalfRightFACE]

You might be eating a lot of sugar in your diet, try cutting out the sugar, you will feel very energized.

[sowilson]

you should look into eating 5 meals a day (more often not necessarily more food per day). Cutting down on processed sugar would be good, and if you're consuming a large amount of protein powder try cutting back on that (for example, don't take any from when you wake up until you work out, then have some after your lift). You may consider adding a bit of caffeine in your diet prior to your work out. If you try these things and don't see any effect you might consider seeing a nutritionist.