While a calorie deficit is the only requirement for weight loss and fat loss, the ratio of macronutrients, or "macros", consumed can be very helpful for satiety signals, as well as body composition. Consuming adequate protein, carbohydrates, and fats will help to ensure that you are promoting overall health and your body is functionally optimally. Moreover, consuming adequate protein and fiber can help to promote feelings of fullness, which makes sticking to a calorie deficit much easier, and consuming adequate protein will help to reduce the loss of lean muscle mass.