Okay I'm 17 and am a sprinter on my high schools track team and we do INTENSE workouts I was thinking about taking whey protein shakes after hearing my friends suggest it . But I've heard it makes you gain weight. And I've also heard that with a lot of cardio it actually makes you lose muscle. Is that true ? If so any protein suplents tht could benefit me ?
As a sprinter, you are using mostly anaerobic energy systems. The adaptations that your body will produce in response to your sport means an increase in fast-twitch muscle fibers, which are typically larger than slow twitch (which are higher in distance runners). This means larger size, but may not mean heavier weight. As a sprinter, you want fast-twitch.
Whey will not make you lose muscle. A high caloric expenditure combined with a caloric deficit will make you lose muscle.
Whey protein is typically structured to be absorbed faster than other proteins, as it is easier to break down, in contrast to something like casein protein. Casein protein takes longer to break down, but can be beneficial if you're trying to keep your protein levels and basal metabolic rate high.
Remember-the high caloric expenditure makes you lose muscle. The body draws energy from carbohydrates, fats, and proteins (in that order (layman's terms)). If it runs out of readily available energy sources, it will begin to draw from your own body, breaking down protein. That's where the weight loss comes from. I'm oversimplifying it, but let me know if I need to expand.
So to answer your question, no, whey will not make you lose weight. Not feeding yourself enough to match the amount of work you're doing will.
As a sprinter, you must find out how many calories you burn in an average training session. Typically I would feed a sprinter a diet rich in carbohydrates, then protein, then fat last of all. You're going to use carbohydrates first, but protein is absolutely necessary to build more muscle (so you can use MORE carbohydrates!). You likely won't touch fat when sprinting. If your body does so, you're likely training too long.
Protein intake is used to help with muscle growth. Muscles weigh more so yes, in that way it could be said that it might make you gain some weight. But if your workouts are that intense, I would not worry about that and read the label on back of the protein powder too - some have added sugar. This article has a good guideline for how to start figuring out what your intake should be.
If you have a dairy sensitivity you might want a protein powder without whey. Some people I know have gotten over dairy sensitivity by also taking probiotics. Make sure you have enough fiber and water in your diet so the protein shake doesn't make you constipated. I would try a brand out and see if your body likes it.
Regarding lots of cardio and losing muscle: I don't think that will happen to you because you are a sprinter not a marathoner. Your work-outs are totally different. As a result, marathoners have smaller looking muscles but with greater endurance than sprinters.