Updated: Dec 21, 2021
The three macronutrients are protein, carbohydrates and fat. If you are looking to track what you eat, even if for a short period of time so you know where to aim in the future, this is how you should set up your macros. I will use examples for someone who weighs 180lb and consumes 3000 calories per day.
Protein: Roughly 1g per lb of bodyweight. This can be increased to your preference, as protein is highly satiating (filling) and has a high thermic effect (as discussed in issue #1). For someone who weighs 180lb, this will be 180+g of protein, noting that 1g of protein has 4 calories, equating to 720 calories.
Fat and carbohydrates: Everyone reacts differently to these macronutrients, with this largely depending on your ethnic background - this is why replicating someone else's macronutrient split won't provide the same results for you. Here you must be your own best expert to determine what works best for you in the situation you are in - this will take time and patience, but trust your intuition.
Fat: A minimum of 25% of your caloric intake. For someone consuming 3000 calories, this will be 750 calories, and since 1g of fat has 9 calories, this equates to 83g. Increase this to your preference (as your own best expert).
Carbohydrates: Fill in the remaining calories. Following on from the example: 3000 (total) - 720 (protein) - 750 (fat) = 1,530 calories remaining. Since 1g of carbohydrates has 4 calories, so this equates to 382.5g of carbohydrates. Noting that this is the maximum value as we used the minimum fat intake.