Well, to cycle calories you would have to adjust one of the three macro-nutrients (protein, carbs, and fat). Protein should always remain somewhat high if your weight training.
Fats are usually kept constant throughout the week or even inversely proportioned to your carb intake (this is because carbs are your body’s main fuel source, with fats as a second favorite. Your body wouldn’t need a ton of fuel from both carbs and fat in the same day, this is why they are opposite in relation.
For example, if carbs are high, fat is low and vice versa. Often you see fats kept low through out the week so calories will be really low on low carb days). The reason why carbs are cycled is because the digestion of carbs leads to insulin, which is anabolic (especially on high days). Carbs are also the easiest to manipulate with its storage.
If your glycogen is depleted, most, if not all of your carbs (with in reason) will be stored in the muscles. When carbs are high (at 4cals a gram, so are calories and vice versa). Carbs just become the naturalist, simplest way to cycle calories with out much effort. That was long winded and a little off track sorry.