It's true, you must have a calorie deficit, but some people overdo their calorie deficits (a 1,000 calorie deficit or more), and it burns off a lot of muscle. High protein diets, weight lifting, and cardio combined with a calorie deficit of 500 calories or less will preserve lean muscle mass. If you burn off muscle, you'll look like a coat rack and that's never sexy, especially for a man. Moreover, muscle will also burn off calories as it is metabolically active tissue.
Low carb diets used with carb cycling will burn off the extra fat that normal low calorie dieting won't shake off, this is especially effective if you want a six-pack and apollo's belt.
Some people have different ways of using carb cycling. One way is to do a low carb diet for three days, then the fourth day have a high carb day. Of course, never carb load on candy, white bread, white rice, white pasta, or pizza on your high carb day.
Another way is to eat starchy carbs on your weight lifting days, such as whole grain rice, whole grain pasta, beans, whole grain bread, potatoes, corn, peas, carrots; and eat non-starchy carbs on your cardio days such as radishes, celery, mustard greens, kale, lettuces, spinach, Asparagus, broccoli, peppers. This is wear blending becomes extremely useful.
Carb cycling should prevent the exhausted, cranky, and brain-fogged symptoms.