too much protein?

I eat a lot of proteins. Today, for example, I ate a turkey sandwich (~5-10 grams of protein), a can of tuna fish (37.5 grams), and about 4 servings of milk (32 grams), among other things that probably had small amounts of protein in them. That's over 75 grams of protein total. I'm 17--no longer a growing boy, but still active--and I lift weights 5 times a week. But do I really need that much protein? Or is 75 grams a normal amount? The FDA doesn't include the percent of daily value when it comes to proteins (not that I really go by what they say, anyway) and everyone tells us to eat animal and plant proteins, but nobody tells us how much.

Can any of you offer prose on the pros of proteins for a teen?

That is not an excessive amount of protein. While you may not grow taller, most 17 year-olds still have some filling out left to do.
When individuals have medical conditions such as kidney failure which require protein restriction, we usually restrict them to 0.5 - 0.7 mg protein/kg (or 0.24 -0.32 mg/lb) daily. For healthy individuals, usually 20-30% of calories should come from protein - at 4 Cal/mg protein, you're getting ~ 300 Cal/day from protein. Presumably, you're also aiming for more than 1000-1500 Cal/day, so you could EASILY increase your protein intake.
I'm no expert in body-building nutrition, but many gym rats take protein supplements with the idea that it takes protein to build protein...

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Sue from El Paso

[Markxxx]

A person can only digest so many grams of protien (something like 30gr) per every 4 hours. If you eat more than that during that time span it will simply be converted and stored eventually as fat. (a bit oversimplified there but you get the idea)

[JAB]

To store nutrients as fat you need to have carbohydrates as well. If you eat more protein than your body can process, it just passes through (this can be hard on the kidneys, though).

In regards to the original question - if you aren't getting enough protein, your body will start to consume its own protein stores, which we usually call "muscle". If you aren't losing muscle, you are getting enough protein.