My opinion (and I must stress it is only an opinion) is that carbs are the area to watch.
Calories are not necessarily an effective measure of the impact food has your body. The theory that weight gain or loss is the net difference between calories in and calories expended doesn't actually stack up very well. Your body doesn't have a magic timer that goes ping at midnight and then say "Well, today I've used 2,300 calories. But I've burned 2,100 today, so let's store 200 as fat".
Your body isn't like a petrol tank in a car. The way energy is released in your body is entirely dependent on what your body is doing at the time, and that energy primarily comes from sugar in the blood. If at the time you are doing a physical activity there is not enough sugar entering your blood to sustain the muscles, your body switches to using fat as an energy source - regardless of how many calories you may or may not eat in the day relative to your activity level. Similarly, if there is plenty of sugar entering your blood but you are not actively using it as fuel at that exact moment, it is converted to fat by insulin.
Therefore in weight loss, as a general principle I believe you need to eat in such a way to minimise the amount of glucose entering your blood stream. This encourages your body to use body fat for energy instead and reduces your insulin output - bearing in mind that insulin promotes fat storage and actively blocks fat metabolism, if you are trying to lose weight, the less insulin circulating, the better (provided of course your blood sugar levels are normal).
Therefore while calories do provide a rough benchmark (if you're eating 13,000 cal a day, that's clearly too much for your body's needs overall!), it's your carbohydrate intake that will have the most significant, direct and immediate effect on your weight loss and goals.
It's also worth bearing in mind your meal plan structure too. If we accept that your body burns energy according to a 'just-in-time' principle rather than as a fuel tank, then logically, it would be more effectively to eat small meals frequently, rather than 2-3 large meals a day.