I have been hearing for a while about the golden window of forty minutes. This period of forty minutes just post your workout gives you a golden window when you can eat almost anything, and it gets digested. Apparently, your body achieves superhuman proportions in its ability to consume food. In fact, some even advocate ensuring that you consume protein or carbohydrates or both to make sure that you rebuild lost amino acids and stored glycogen. If you are not on this bandwagon, are you missing out?
Scientists have established that exercise, even moderate amounts, causes a reduction in glycogen storage in your muscles by up to 25-50%. Therefore, naturally, very strenuous exercise does result in depletion. Others have shown that replenishing of your muscle groups occurs when your glycogen stored in muscles is relatively high. The need for a high level of glycogen means that you should be eating something before a workout. Perhaps, a banana. Also, it was found that if you combined carbohydrate and protein in your meal just post your workout, it aided in muscle recovery.
However, these findings need to be taken with a pinch of salt. A significant number of these research reports were conducted on advanced athletes, many of whom were engaging in split training (training the same muscles group twice a day). Other research papers found no significant change in muscle build-up with a protein shake just post a workout. The evidence for a golden window is therefore far from conclusive. So what should one do?
The general advice is that if you are exercising after overnight sleep, consume some form of protein, before a workout. Once done, it does not matter when you eat. If you are exercising just before lunch, ensure that your meal consists of a mix of protein and carbs. There is no golden answer; you need to find what is best suited for your body given age, gender, and form of exercise.