Weight training is a different animal than most any other sport when it comes to consuming calories while working out. Unless you are lifting for several hours at one time, there isn’t really a sufficient amount of time to utilize a mass amount of macro’s while you lift. Not to mention that you really want all available blood flow to be going to the skeletal muscles and not your GI tract. The majority of lifters can get through a routine in 45-90 minutes, which is optimal for best results if done consistently through the week. During that time there are a few things you can do to help your lifting session along, however you will get the most bang for your buck by paying close attention to what you are eating when you are NOT in the gym.
Protein- Protein can take a substantial time to break down enough to be utilized in your system for energy and repair. Consuming adequate protein before your workout is going to be most helpful in assisting in muscle gain. Likewise, your post workout protein will facilitate in restoring muscles. Which you can learn more about here.
Carbohydrates- Some lifters may choose to lift a little over 60 minutes or even phasing quick post lifting cardio or sport specific drills into their regimen which may require more glycogen than is available at that time. This is a good time to implement a quick simple carb (half a banana, slice of apple, juice, electrolytes, for example). Outside of those parameters, there shouldn’t be any real need to eat carbs intra workout. Don’t over complicate it, keep it simple.
Fats- During your workout there really isn’t any room for fat consumption. In fact it may even hinder performance at that time. So no cheeseburgers at the squat rack!
Micros- Here is where you can find some help during your workout.
BCAA’s: Once you have depleted your glycogen storage and maybe even taping into your creatine or pre-workout to carry you through the rest of your session you can start sipping your branch chain amino acids. There is much controversy over ALL supplements/nutrition and timing because there isn’t just one method that fits everyone (as I’ve mentioned time and time again). Therefor you’ll need to try a few different tactics and see what works and what doesn’t. Typically you’re looking at around 10-15 g of BCAA’s per workout. If they help you finish your session then they are doing their job. They will also assist with your post workout protein absorption -there’s no need to consume more aminos post lifting, just having it in your system should be enough.
Electrolyte replacement: Keeping a balance of ions in your system is critical for optimal performance. The electrolytes in your body maintain a pretty good balance all on their own when faced with normal conditions and stressors. Should you put extreme stress on your body through long durations of intense exercise you may need to replace some of the electrolytes lost through perspiration. Sometimes weather conditions will also effect your electrolyte balance but typically speaking you should only require an electrolyte replacement if your exercising longer than 60 minutes. At which time you will need to be pretty savvy on what you consume. Too much of any given cation/ion can be just as damaging as too little, so choosing a balanced beverage or food is optimal.
To sum up, there really isn’t any reason to bring a buffet to the weight room. Your body is already under extreme stress and eating adds additional unnecessary stress. So in general, keep it simple during your lifting sessions and your body will thank you.