Originally Posted by 8pack
Why is there not a use for them?
When people first start training, their bodies are still similiar to a non-training person's. Compare this to someone who's been training for 5+ years and has built a higher amount of muscle mass. This person is already probably more aware of their dietary needs, so even they may not "need" supps. That being said, a muscular body that routinely uses those muscles to perform loaded movements that bash the other body systems will be able to use certain things to push itself even harder.
Protein is important to optimize muscle growth and strength development, but you should do your best to get protein from actual foods. If you can't, then bring protein powders into the equation.
The things in fish oil that help us used to be available in foods we would eat all the time. Cows that grow up eating grass in a field produce meat that has just as many omega-3's as salmon. That isn't the case anymore, with grain-fed hormone filled beef in the grocery store, so now we have to get our omegas by adding them back into other things like eggs and fish oil caps.
Things like protein products (including BCAA's), fish oil, and multi-vitamins are there to help optimize how the body performs, if the need is there because of a specific person's dietary limitations. A person who eats grass-fed beef, different types of fish, and plenty of veggies already probably won't benefit from those products. For the record, I don't do any of those things, so I use supps to take up the slack. Hopefully once I get my family moved I'll be able to find a source for grass-fed beef and also start getting more veggies into my diet.
Then there are supps that don't do a single thing directly for the muscles, like pre-workouts. I take these too, because I feel that they help me hit it much harder in the gym, which of course helps me move towards my goals. Supps like this serve a purely psychological purpose, make no mistake about it, and should be the first thing to go if money is tight.