By using carbon intensity, or the ‘per kg’ carbon footprint of a meal, we can fairly rate foods regardless what type of meal it is. If we used a total per serving, it might allow people to manipulate allows us to use the same thresholds when rating breakfasts, lunches, starters, mains, and deserts,   still show whether a meal is A or E in both    This is also why you might see a meal with a higher rating even though the total is lower.