Fill the Concorde with Japanese people and the Airbus A380 with Americans and you'll see a ⬆️⬇️ in the fuel efficiency lol.

✏️ v 🍐

You might not think it matters, but in all seriousness though, the average weight of the passengers on an aircraft, especially one that can hold half of a thousand at 500-800 passengers, the difference in weight between 500 avg Japanese people and 500 avg Americans could be... extremely catastrophic, at 20,000-40,000 pounds difference, enough to sink an airship if it was full of fuel, luggage, and people.