Carbs, your body’s main form of energy during exercise, are found in the blood, muscles and liver. Any carbs you eat are ultimately converted to glucose within 5 minutes to 2 hours. To undertake moderate or hard exercise, you have to have enough carbs available. Eating a chronically low-carb diet may make it more difficult for you to participate in exercise that is harder or longer in duration, but supplementing with carbs during any activity will help you maintain your blood glucose and keep your energy levels higher.
Some fat is used as energy during exercise, particularly when it's lower intensity, although carbs are almost always the preferred fuel (even in a "fat burning" range). Fat is your primary fuel during recovery from exercise, however. When you eat fatty foods, the fully digested fats can raise insulin resistance 4 to 6 hours later and help prevent lows after exercise (and overnight). Limit your intake of trans fats and highly processed fats for better health, though.
It's important to eat enough protein, especially when you're being regularly active. Protein breaks down into amino acids, which are the building blocks of muscles, enzymes, hormones, immune cells, and other structures in your body. Being in motion does increase your protein needs somewhat, especially when you're not eating enough calories. Protein takes 3 to 4 hours to be metabolized and can raise your blood glucose some when it is fully digested, so it can be eaten after exercise to help prevent hypos later on if you are an insulin user.
The best time to use sports products is during exercise or immediately afterwards. Sports drinks contain glucose polymers that can raise blood glucose while hydrating you, but just watch out so you don't consume more carbs than you actually need. Whey protein and other supplements are not necessary for optimal sports performance and muscle growth; just eat enough protein (eggs, lean meats, dairy, legumes, and nuts and seeds) through foods naturally.