The calories within your BMR NEED to contain the following:
Protein for muscle repair, as well as repair of other bodily tissues. Protein allows your muscles to remain tight and lean.
Healthy fats EPA, DHA (you get these from fish) and the 3 ALA's, which come from plants. Healthy fats, although are 9 calories per gram, are essential for keeping the body functioning. This is because the brain, which co-ordinates every single action of the body by sending electrical signals to various part of the body, is a fatty tissue itself, and requires fatty acids to work properly and maintain a high level of hydration and function.
Carbohydrates are important for energy but aren't totally necessary. Most people who gain too much weight tend to overindulge on food like crisps, chocolate, takeaways such as pizza and chinese, biscuits, as well as alcohol such as beer and wine.
Your body only needs nutrients to help maintain healthy bodily tissues such as vital organs (liver, kidney, brain, heart), your muscles, skeletal tissue).
As long as your calorie intake looks after these factors, you'll be fine.
If your BMR is 1400 calories for example, your protein, carbs and fats for the day need to round up to that number.